MECHANISMS OF TRANSMISSION OF PATHOGENIC ORGANISMS

  Introduction

This section of the course presents concepts in the epidemiology and prevention of disease transmission in the health care setting. Upon completion of this module, the learner will be able to:        

Describe how pathogenic organisms may be spread in the health care setting;

Identify the factors which influence susceptibility to infection;

Define strategies to reduce the transmission of pathogenic organisms;

Describe how infection control concepts are applied in practice.

  

Which framework is most frequently used to describe the transmission of pathogenic organisms in the health care setting?

The Chain of Infection is the epidemiologic model most commonly used to describe the spread of infection in the health care setting. According to this model, infection can only develop when specific elements are in place. These elements are represented as distinct links in a chain. The elimination of any one link or factor will prevent infection from taking place. This circumstance is referred to as a “break in the chain of infection.”

Transmission of infectious agents requires a source (or reservoir) of infectious agents with a portal of exit; a susceptible host with a portal of entry receptive to the agent; and a mode of transmission for the agent.

Sources of infectious agents

Causative agents of disease include bacteria, viruses, fungi, parasites and prions. In the health care setting, infectious agents derive primarily from human sources, but parts of the inanimate environment may also be a source of transmission.

Human reservoirs include patients, health care personnel, household members and visitors. Such source individuals may be symptomatic with obvious signs of active infection; or may be

asymptomatic as is seen in subclinical cases and in carriers. Symptoms are not always present during the incubation period of an infectious disease. Also, individuals may be transiently or chronically colonized with pathogenic microorganisms, particularly in the respiratory and gastrointestinal tracts.

Health care providers should be alert to patients with signs and symptoms of communicable diseases that are prevalent in their community. Diagnostic testing is recommended to confirm infection in persons who may be asymptomatic carriers of potentially transmissible disease. Antimicrobial agents, used when appropriate to treat cases of infection, can eliminate the reservoir and prevent the spread of infection.

In addition to treating patients with communicable disease, environmental controls, such as proper ventilation, should be in place for any facility that may treat patients with airborne infections (e.g., tuberculosis). It is important to consider the safety of both health care providers and patients when populations at risk for airborne diseases are present. Proper environmental controls can reduce the spread of infection from reservoirs.

  Susceptible Host

Infection is the result of a complex interrelationship between a potential host and an infectious agent. The immune state at the time of exposure to an infectious agent, interaction between pathogens, and virulence factors intrinsic to the agent are important predictors of an individual’s outcome.

There is a spectrum of possible outcomes following exposure to an infectious agent. Some persons exposed to pathogenic microorganisms never develop symptomatic disease while others become severely ill and even die. Some individuals are prone to becoming transiently or permanently colonized but remain asymptomatic. Still others progress from colonization to symptomatic disease either immediately following exposure, or after a period of asymptomatic colonization.

Host-specific factors that affect immunity and influence the potential for infection include:

Extremes of age: Newborns and the elderly are more susceptible to disease/infection than the general population.

Presence of underlying disease/infection: Disease which directly impacts the immune system (e.g., cancer, autoimmune disorder) will markedly reduce an individual’s resistance to pathogenic organisms. In general, persons weakened by the presence of any disease/infection will be more susceptible.

Lifestyle: Personal habits may impact susceptibility to communicable diseases. For example, alcoholics are more susceptible to pneumonia caused by organisms such as Mycobacterium tuberculosis or Klebsiella pneumoniae. At the same time, healthy behavior (such as regular exercise) will increase resistance to disease.

Nutritional status: Poor nutrition will weaken the immune system, thereby increasing susceptibility to disease. Alternatively, good nutrition will strengthen the immune system, thereby enhancing the ability to ward off disease.

Natural and Passive immunity: Natural immunity to a disease (e.g., chicken pox) may be acquired as a result of the development of antibodies which follows infection with the causative agent. The existence of these antibodies will prevent recurrence of a specific disease. Active immunization (e.g., through vaccination or toxoid administration) and passive immunization (e.g., through immune globulin or antitoxin administration) also play an important role in the prevention of communicable disease.

Trauma and Invasive or Surgical procedures: These factors serve to compromise the integrity of the body’s natural barriers to disease resulting in an increased susceptibility to infection.

Medications: Certain medications (e.g., antimicrobial agents, gastric acid suppressants, corticosteroids, antirejection drugs, antineoplastic agents, and immunosuppressive drugs) directly affect the body’s immune system and may increase susceptibility to disease. Long-term antibiotic treatment can disrupt the body’s normal flora and result in increased susceptibility to antibiotic-resistant organisms.

Indwelling devices: Synthetic implants and patient care devices such as urinary catheters, endotracheal tubes, central venous and arterial catheters facilitate development of infection by allowing potential pathogens to bypass local defenses that would ordinarily impede their invasion and by providing surfaces for development of “biofilms” that may facilitate adherence and growth of microorganisms.

  Modes of Transmission

The modes of transmission vary by type of organism. Some are transmitted primarily by direct or indirect contact, (e.g., Herpes simplex virus, respiratory syncytial virus, Staphylococcus aureus); and others by the droplet (e.g., influenza virus, B. pertussis) or airborne routes (e.g., M. tuberculosis). Other infectious agents, such as bloodborne viruses (e.g., hepatitis B and C viruses and HIV) are transmitted rarely in health care settings, via percutaneous or mucous membrane exposure. Not all infectious agents are transmitted from person to person and some infectious agents may be transmitted by more than one route.

(1)  Contact transmission is the most common mode of transmission. It is divided into two subgroups: direct contact and indirect contact.

Direct contact transmission occurs when microorganisms are transferred from one infected person to another person without a contaminated intermediate object or person. Examples of direct contact transmission between patients and health care personnel include:

The blood from a patient directly enters a caregiver’s body through contact with a mucous membrane or  breaks (i.e., cuts, abrasions) in the skin.

Herpetic Whitlow

Mites from a scabies-infested patient are transferred to the skin of a caregiver while he/she is having direct ungloved contact with the patient’s skin.

A health care provider develops herpetic whitlow on a finger after contact with Herpes simplex virus (HSV) when providing oral care to a patient without using

Indirect contact transmission involves the transfer of an infectious agent through a contaminated intermediate object or person. Examples of opportunities for indirect contact transmission include:

Patient-care devices (e.g., electronic thermometers, glucose monitoring devices) may transmit pathogens if devices contaminated with blood or body fluids are shared between patients without cleaning and disinfecting between patients.

Shared toys may become a vehicle for transmitting respiratory viruses (e.g., respiratory syncytial virus) or pathogenic bacteria (e.g., Pseudomonas aeruginosa) among pediatric patients.

Instruments that are inadequately cleaned between patients before disinfection or sterilization (e.g., endoscopes or surgical instruments) or that have manufacturing defects that interfere with the effectiveness of reprocessing may transmit bacterial and viral pathogens.

 

(2)  Droplet transmission occurs when respiratory droplets carrying infectious pathogens transmit infection as they travel directly from the respiratory tract of the infectious individual to susceptible mucosal surfaces of the recipient. Droplets are generated when an infected person coughs, sneezes, or talks; or during procedures such as suctioning, endotracheal intubation, cough induction, and cardiopulmonary resuscitation. The distance that droplets travel depends on the velocity and mechanism by which respiratory droplets are propelled from the source, the density of respiratory secretions, environmental factors such as temperature and humidity, and the ability of the pathogen to maintain infectivity over that distance. Based on these considerations, it may be prudent to don a mask when within 6 to 10 feet of the patient, especially when exposure to emerging or highly virulent pathogens is likely. Examples of infectious agents that are transmitted via the droplet route include Bordetella pertussis, influenza virus, adenovirus, rhinovirus, Mycoplasma pneumoniae, SARS-associated coronavirus, group A streptococcus, and Neisseria meningitides.

 

(3)  Airborne transmission occurs by dissemination of either airborne droplet nuclei or small particles in the respirable size range containing infectious agents that remain infective over time and distance. Microorganisms carried in this manner may be dispersed over long distances by air currents and may be inhaled by susceptible individuals who have not had face-to-face contact with (or been in the same room with) the infectious individual. Preventing the spread of pathogens that are transmitted by the airborne route requires the use of special air handling and ventilation systems (e.g., Airborne Infection Isolation Rooms or ‘AIIR’) to contain and then safely remove the infectious agent. Infectious agents to which this applies include Mycobacterium tuberculosis, rubeola virus (measles), and varicella-zoster virus (chickenpox).  Variola virus (smallpox) is known to be transmitted via droplet and contact routes; however, published data suggest that this virus may remain airborne over long distances under unusual circumstances and AIIRs are recommended for housing suspected cases. In addition to AIIRs, respiratory protection with NIOSH certified N95 or higher level respirator is recommended for health care personnel entering the AIIR to prevent acquisition of airborne infectious agents such as M. tuberculosis.

Throughout this curriculum, methods for controlling the transmission of pathogenic organisms will be discussed. Proper hand washing, proper use of personal protective equipment, management of patients with communicable diseases, and techniques for sterilization / disinfection will all be explained in greater detail.

Other types of transmission

Transmission of infection from sources other than infectious individuals includes those associated with common environmental sources or vehicles such as contaminated food, water, or medications (e.g., intravenous fluids). Vectorborne transmission of infectious agents from mosquitoes, flies, rats, and other vermin also can occur but are not a major consideration in health care settings in the United States.

What is the single most important measure in breaking the chain of infection?          

Hand hygiene: Contact with the hands of health care workers is the primary cause of patient exposure to pathogenic organisms. Proper hand hygiene is the most effective way to reduce the spread of infection to patients and to other health care workers.

What is the proper way to wash the hands?           Hand washing instructions: Wet the hands with warm running water. Apply soap and work up a lather for 10 - 15 seconds, while rubbing all surfaces of the hands. Pay close attention to washing between fingers, around nail beds, and underneath the nails. Duration of washing is important to assure mechanical removal of debris and allow antimicrobial solutions sufficient contact time to achieve the desired effect.          After washing the hands, use a paper towel to turn off the water tap. Do not touch the water tap with freshly washed hands as this will result in re-contamination of the skin. Many health care facility basins are equipped with wrist blades, foot pedals, or automatic water flow sensors. Such devices provide more sanitary water delivery.

Health care workers with long fingernails need to be especially careful about proper hand washing, since microorganisms can live beneath the nails. Artificial nails and chipped nail polish support the growth of large numbers of bacteria and should be avoided. Natural nails should be less than one quarter of an inch in length. This is particularly important for providers that have regular contact with patients at high risk of acquiring infections, e.g., patients in intensive care units or in transplant units.

Hands should be decontaminated:

when visibly soiled with blood or other body fluids.

before having direct contact with patients.

before donning sterile gloves for placement of a central intravascular catheter.

before inserting indwelling urinary catheters, peripheral vascular catheters, or other similar invasive devices.

after contact with a patient's intact skin (e.g., when taking a pulse or blood pressure, and lifting a patient).

after contact with body fluids or excretions, mucous membranes, nonintact skin, and wound dressings if hands are not visibly soiled.

if moving from a contaminated-body site to a clean-body site during patient care.

after contact with inanimate objects (including medical equipment) in the immediate vicinity of a patient.

after removing gloves.

before eating and after using a restroom.

What kind of soap should be used to wash the hands?  

Health care facilities can choose from an array of soap products on the market. Given the wide variety available, the selection of the proper soap requires careful consideration. Staff acceptance of the product is the most important concern. If staff do not like the soap, they are less inclined to use it. Cost-effectiveness is another important consideration.

Antimicrobial soaps (e.g., chlorhexidine gluconate, PCMX, iodophors) should be available in areas where invasive procedures are performed. Such soaps should also be used in special care units and in areas that house patients infected with antibiotic-resistant organisms. Standard soap is acceptable for use in visitor areas or areas where patient care does not require direct contact with body fluids.

If bar soap is used, it should be placed on racks that allow for adequate water drainage. Pools of water, which accumulate around bars of soap, can be reservoirs for pathogenic organisms (e.g., bacteria). 

Dispensers used for liquid soap should be checked for caking around the delivery spout. Soap residue that accumulates around the dispenser can also be a reservoir for infectious agents. Liquid soap should not be added to a partially empty soap dispenser. This practice of "topping off" dispensers can lead to bacterial contamination of soap.

Waterless alcohol-based antiseptic hand gels have grown in popularity because they may conveniently placed in areas of a health facility where sinks and plumbing are not present. Recent research has shown that these formulations can be more effective than antimicrobial soap in reducing bacterial counts on the hands of health care workers thereby preventing the transmission of potentially harmful bacteria between workers and patients. Some studies have demonstrated that skin dryness caused by alcohol-based solutions is equivalent to or less severe than dryness caused by standard antiseptic hand washing solutions.

There are several important considerations before implementing an alcohol-based hand washing system.

Alcohol-based solutions are flammable and should be stored appropriately. Alcohol-based formulations vary in consistency, fragrance, skin conditioning agents, and

drying time. These factors may influence staff acceptance and use of the product. Similar to other hand washing products, dispenser systems vary and may be prone to

problems such as clogging. Alcohol-based gels and rinses may be more expensive than other types of antiseptic hand

washing solutions.

When using an alcohol-based handrub, apply the product to the palm of one hand and rub both hands together, covering all surfaces of hands and fingers, until hands are dry. Note that the volume needed to reduce the number of bacteria on hands varies by product.

Hands that are visibly dirty or contaminated with proteinaceous material, blood or body fluids, should be thoroughly washed with soap and water. Waterless alcohol-based hand washing agents are not recommended for hand hygiene in this circumstance.

None of the currently available antimicrobial agents used in antiseptic handwash or antiseptic hand-rub preparations are capable of killing spore-forming bacteria such as Clostridium difficile or Bacillus anthracis (anthrax). When caring for patients with C. difficile associated diarrhea, health care workers should wash hands with soap and water to physically remove spores from the surface of contaminated hands. Persons with suspected or documented exposure to B. anthracis-contaminated items also should be encouraged to wash their hands with soap and water.

Before implementing any new system of hand washing, it is good practice to have staff perform a thorough evaluation of the product. Staff acceptance will facilitate compliance with hand washing protocols.

The most recent expert guidelines and materials to promote hand hygiene in a health care facility may be found on the CDC website at the following address: http://www.cdc.gov/handhygiene/.

What else can a health care worker do to break the chain of infection? 

Standard Precautions combine the major features of Universal Precautions and Body Substance Isolation and are based on the principle that all blood, body fluids, secretions, excretions (except sweat), non-intact skin, and mucous membranes may contain transmissible infectious agents. It constitutes the primary strategy for the prevention of health care-associated transmission of infectious agents among patients and health care personnel.

Standard Precautions include a group of infection prevention practices that apply to all patients, regardless of suspected or confirmed infection status, in any setting in which health care is delivered. These practices include: hand hygiene; use of gloves, gown, mask, eye protection, or face shield, depending on the anticipated exposure; and safe injection practices. Also, equipment or items in the patient environment likely to have been contaminated with infectious body fluids must be handled in a manner to prevent transmission of infectious agents (e.g. wear gloves for direct contact with heavily soiled equipment; properly clean and disinfect or sterilize reusable equipment before use on another patient).

Transmission-Based Precautions are for patients who are known or suspected to be infected or colonized with infectious agents (including multiple drug resistant organisms) which require control measures in addition to Standard Precautions to effectively prevent transmission. Since the infecting agent may not be known at the time of admission to a health care facility, Transmission-Based Precautions should be applied based on the clinical syndrome and the likely etiologic agents. When the pathogen is identified or the infectious etiology is ruled out, precautions are modified accordingly.

There are three categories of Transmission-Based Precautions: Contact Precautions, Droplet Precautions, and Airborne Precautions. For diseases that have multiple routes of transmission (e.g., SARS), more than one Transmission-Based Precautions category may be used. When used either singly or in combination, they are always used in addition to Standard Precautions.

Contact Precautions are intended to prevent transmission of infectious agents which are spread by direct or indirect contact with the patient or the patient’s environment; and where the presence of excessive wound drainage, fecal incontinence, or other discharges from the body suggest an increased potential for extensive environmental contamination and risk of transmission. Contact Precautions is the category of isolation most frequently applied when patients are found to have “epidemiologically important” pathogens that are resistant to first line therapies, have a propensity for transmission and are associated with serious clinical disease. This includes MRSA (Methicillin Resistant Staph aureus), VRE (Vancomycin Resistant Enterococcus species), and Clostridium difficile.

A single-patient room is preferred for patients who require Contact Precautions. When a single-patient room is not available, consultation with an infection control specialist is recommended to assess the feasibility and risks associated with other options such as cohorting or keeping the patient with an existing roommate. Personnel caring for patients on Contact Precautions should wear a gown and gloves for all interactions that may involve contact with the patient or potentially contaminated areas in the patient’s environment.

Droplet Precautions are intended to prevent transmission of pathogens spread through close respiratory or mucous membrane contact with respiratory secretions. Because these pathogens do not remain infectious over long distances in a health care facility, special air handling and ventilation are not required to prevent droplet transmission. Infectious agents for which Droplet Precautions are indicated include B. pertussis, influenza virus, adenovirus, rhinovirus, N. meningitides, and group A streptococcus (for the first 24 hours of antimicrobial therapy). A single patient room is preferred for patients who require Droplet Precautions. When a single-patient room is not available, consultation with an infection control specialist is recommended to assess the feasibility and risks associated with other options such as cohorting or keeping the patient with an existing roommate. Health care personnel should wear a mask (a respirator is not necessary) for close contact with infectious patient; the mask is generally donned upon room entry.

Airborne Precautions prevent transmission of infectious agents that remain infectious over long distances when suspended in the air (e.g., rubeola virus [measles], varicella virus [chickenpox], M. tuberculosis, and possibly SARS-CoV). The preferred placement for patients who require Airborne Precautions is in an airborne infection isolation room (AIIR). An AIIR is a single-patient room that is equipped with special air handling and ventilation capacity. In settings with limited isolation options such as physician offices, masking the patient, placing the patient in a private examination room with the door closed, and providing respirators or masks to all staff will reduce the likelihood of airborne transmission until the patient is either transferred to a facility with an AIIR or returned to the home environment, as deemed medically appropriate. Health care personnel caring for patients on Airborne Precautions should wear a mask or respirator prior to room entry. Whenever possible, non-immune workers should not care for patients with vaccine-preventable airborne diseases (e.g., measles, chickenpox, and smallpox).

Other important measures for reducing the risk of disease transmission include:

Environmental control measures such as effective housekeeping procedures; appropriate ventilation; safe handling of visibly contaminated linen and potentially infectious waste.

Implementation of safe medical devices and safe patient care practices. Assuring worker and patient protection through availability of vaccination and post-

exposure prophylaxis. Training and education of health care workers to assure understanding of concepts in

disease transmission and methods of transmission.

REMEMBER: Whatever precautions may be taken, PROPER HAND HYGIENE---both before and after patient care---is the MOST EFFECTIVE way to reduce the spread of infection.

ENGINEERING AND WORK PRACTICE CONTROLS WHICH REDUCE THE RISK OF PATIENT AND HEALTHCARE WORKER EXPOSURE TO INFECTIOUS

MATERIAL IN ALL HEALTHCARE SETTINGS

Introduction           

This section of the course presents information on environmental controls, specialized devices, and work practice techniques which significantly reduce the risk of patient and healthcare worker exposure to infection.       

Upon completion of this module, the learner will be able to:          

Define the terms "engineering controls" and "work practice controls";

Identify engineering controls and work practice controls which reduce the risk of exposure to infection;

List exposure prevention strategies;

Describe patient care procedures and settings that involve an increased risk of exposure to infectious material.

   What type of controls are available to protect patients and health care workers from exposure to infectious material?

Engineering controls - equipment, devices, and instruments which isolate or remove hazards.          Work practice controls - methods of task performance which reduce or eliminate the risk of exposure to infectious materials.         Personal protective equipment - specialized clothing or equipment worn by health care workers to reduce the risk of exposure to hazards. (Note: Detailed information regarding personal protective equipment is provided in Element 4.)

         What practices and procedures are considered high risk for exposure to infectious body fluids?           Percutaneous exposure to potentially infectious body fluid occurs through injury with a contaminated sharp medical device such as a needle or scalpel.

The most recent data from hospitals participating in the CDC National Surveillance System for Hospital Health Care Workers (NaSH) and from hospitals participating in the EPINet research database show that hollow-bore needles, such as hypodermic needles and winged-steel (butterfly-type) needles, account for nearly 62% of all percutaneous injuries. Suture needles account for 21% of all percutaneous injuries.

The data demonstrated that the following activities are associated with an increased risk of injury with a hollow-bore needle:

Two-handed recapping.

Transferring a body fluid between containers.

Failure to properly dispose of used needles in puncture-resistant sharps containers.

Manual disassembly of needle devices after they are used - e.g., pre-filled cartridge syringes and phlebotomy needle/vacuum tube assemblies.

Handling of needles attached to a length of flexible tubing - e.g., butterfly needles, and needles attached to I.V. tubing.

Insertion and withdrawal of needles from I.V. ports.

Handling or passing a device during or after use.

Other causes of percutaneous exposure to infectious body fluids include injury with contaminated suture needles especially while performing blind suturing; and injury with contaminated broken glass tubes, bone spicules and metal fragments.

In addition to percutaneous injuries, health care workers can be exposed to potentially infectious body fluids through contamination of mucous membranes or non-intact skin. Procedures that generate aerosol sprays or splashing of fluid, such as irrigation or suctioning, can place the health care worker at risk of exposure to potentially dangerous pathogens.

   What engineering controls are available for reducing exposure to infectious body fluids?       

"Safe" needle systems and "needleless" systems.

Many manufacturers of syringes and devices that require the use of needles produce systems with built-in safety features.

Examples include:

syringes or scalpels with a sliding sheath that shields the attached needle or blade after use;

 

needles that retract into a syringe after use;

 

 

blunt tipped needles and catheters.

These features are designed to reduce the risk of health care worker injury during and after invasive procedures (e.g., blood drawing, injections). In addition, several manufacturers have created systems which eliminate the use of needles for certain procedures, such as the administration of intravenous fluids and medications through primary (e.g., heparin lock) and secondary ports.

In November, 1999, the Occupational Safety and Health Administration (OSHA) issued a revised compliance directive for the bloodborne pathogens standard. The revision now specifies that "safer medical devices, such as sharps with engineered sharps injury protections and needleless systems" constitute an effective engineering control, and must be used where feasible. The standard is enforced directly by OSHA in several states. As of June 2002, twenty-one states have enacted some type of legislation related to health care worker bloodborne pathogen exposures. New York has enacted legislation based on the OSHA directive and enforcement is managed by state or local agencies.

Puncture resistant containers for sharps disposal.

Standard garbage pails should NEVER be used for the disposal of syringes and other sharp devices. Federal and state regulations require that needles and sharps be discarded in specially designed, puncture-resistant containers. These are commonly referred to as “Sharps Containers.” Such containers should be strategically located so that clinicians performing procedures can quickly dispose of used sharps without recapping. This will decrease the likelihood of injury and exposure.

The National Institutes of Occupational Safety and Health (NIOSH) published guidelines entitled “Selecting, Evaluating, and Using Sharps Disposal Containers”. This document is intended to assist health care providers in selecting sharps disposal containers and evaluating their efficacy as part of an overall needle stick injury prevention plan. See the course references for more information on this topic.

Laboratory safety equipment.

Some laboratory equipment (e.g., biological safety cabinets, splatter shields) is designed to protect workers from accidental exposure to infectious body fluids. In addition, laboratory

equipment often includes safety features (e.g., locking covers on centrifuge devices) which reduce the risk of exposure to infectious material.

 

   What engineering controls are available for reducing exposure to airborne pathogens?       

Ventilation systems.

Maintenance of adequate ventilation is essential for the reduction of airborne pathogen transmission to health care workers and patients. The flow of fresh air through patient care areas will dilute the concentration of airborne pathogens and reduce the risk of infection from pathogen inhalation. A minimum of six to twelve air exchanges per hour is required in isolation rooms and in other areas which house patients with suspected or confirmed infections which may be transmitted through the air (e.g., tuberculosis).

Negative pressure rooms.

Most rooms are under positive pressure. This means that the air flows from the room into the corridor when the door is opened. If a patient with an airborne infection is in the room, air currents may carry pathogens into the corridor resulting in potential transmission of disease to persons outside of the room. In a negative pressure room, the air flows from the corridor into the room. This design prevents the escape of airborne pathogens from the room. Isolation rooms and other areas that house patients with airborne infections must be maintained under negative pressure at all times.

High Efficiency Particulate Air filters.

High efficiency particulate air (HEPA) filters are used to reduce the volume of airborne pathogens. Air filtration devices equipped with HEPA filters are available to both health care facilities and consumers. HEPA filters vary based on the efficiency (expressed as a percentage) with which pathogens are removed. The proper HEPA filter for specific use depends on the size of the particles which must be removed. HEPA filters designed for airborne pathogen reduction must be capable of capturing particles less than five microns in size. If a hospital employs central air conditioning or heating systems, air from isolation rooms will circulate through the facility. In this case, the isolation room exhaust system must be equipped with the appropriate HEPA filter and the filter should be monitored regularly to ensure its proper operation.

Which work practice controls are effective for reducing exposure of patients and staff to infectious body fluids?

Proper handling and disposal of contaminated needles and sharps.

In general, do not re-cap used needles or syringes.

If it is absolutely necessary to re-cap, the one-handed scoop method should be employed. This is accomplished as follows:

1. Place the sheath on a hard surface;

2. Scoop the sheath up onto the needle using one hand;

3. Be sure that the needle is fully covered;

4. Snap on the sheath using the other hand.

HEALTH CARE PROVIDERS MUST EXERCISE EXTREME CARE WHEN HANDLING AND DISPOSING OF CONTAMINATED NEEDLES AND SHARPS.

Dispose of sharps in puncture-resistant containers. Never dispose of sharps in ordinary garbage pails.

Keep sharps disposal containers readily available. Never use a mattress as a pin-cushion. Never place used syringes on a patient’s bed, where they may become hidden in the linen.

Be especially alert when handling sharps in areas where invasive procedures are being performed (e.g., operating room) and establish “safe zones” for passing instruments.

Intravenous line insertion and blood-drawing procedures should only be performed in well-lit areas.

Get assistance when performing procedures on a combative patient.

If possible, use forceps, suture holders, or other instruments for suturing instead of holding tissue with fingers.

Disassemble sharp instruments by using forceps or other devices.

Enforcement of safe injection practices.

Several CDC investigations of outbreaks of Hepatitis B virus (HBV) and Hepatitis C virus (HCV) among patients in ambulatory care facilities (a private medical practice, a pain clinic, an endoscopy clinic, and a hematology/oncology clinic) in the United States revealed that the viruses were spread as a result of unsafe injection practices. The primary breaches in infection control practice that contributed to these outbreaks were: (1) reinsertion of used needles into a multiple-dose vial or solution container (e.g., saline bag) and (2) use of a single needle/syringe to administer intravenous medication to multiple patients. Preparation of medications in the same workspace where contaminated needles and syringes were dismantled was noted to be a contributing factor in one outbreak.

In a recent outbreak of Hepatitis C infection at an endoscopy clinic in Nevada, it was observed that a clean needle and syringe were used to draw anesthetic medication (propofol) from a single-use vial followed by direct injection into an intravenous catheter in the patient's arm. When the patient required more sedation, the used needle was removed from the syringe barrel and replaced with a new needle; the new needle with the old syringe barrel was then used to draw more medication from the vial. Backflow from the prior injection into the patient's intravenous catheter contaminated the syringe barrel with HCV and subsequently contaminated the contents of the vial. The contaminated medication remaining in the vial was then used to sedate other patients.

Outbreaks such as these can be prevented by adhering to safe injection practices which include the following:

Use aseptic technique to avoid contamination of sterile injection equipment.

Do not administer medications from a syringe to multiple patients, even if the needle or cannula on the syringe is changed.  Needles, cannulae and syringes are sterile, single-use items and should never be reused for another patient or to access a medication or solution that might be used for a subsequent patient.

Use fluid infusion and administration sets (i.e., intravenous bags, tubing and connectors) for one patient only and dispose appropriately after use. Consider a syringe or needle/cannula contaminated once it has been used to enter or connect to a patient’s intravenous infusion bag or administration set.

Use single-dose vials for parenteral medications whenever possible.

Do not administer medications from single-dose vials or ampules to multiple patients or combine leftover contents for later use.

If multidose vials must be used, both the needle or cannula and syringe used to access the multidose vial must be sterile. If a medication vial has already been opened, the rubber septum should be disinfected with alcohol prior to piercing it.

Do not keep multidose vials in the immediate patient treatment area and store in accordance with the manufacturer’s recommendations; discard if sterility is compromised or questionable.

Do not use bags or bottles of intravenous solution as a common source of supply for multiple patients.

Never leave a needle or other device (e.g. “spikes”) inserted into a medication vial septum or IV bag/bottle for multiple uses. This provides a direct route for microorganisms to enter the vial and contaminate the fluid.

Medication vials should be discarded upon expiration or any time there are concerns regarding the sterility of the medication.

 

Preventing contamination of mucous membranes and non-intact skin.

In addition to wearing personal protective equipment (to be discussed later in detail), safe work practices should be employed to prevent mucous membranes and non-intact skin from contact with potentially infectious material.

Keep contaminated gloved and ungloved hands from touching the mouth, nose, eyes, or face.

Position patients in a manner to direct sprays and splatter away from the face of the caregiver.

Assure that protective equipment is secure and comfortable before patient contact to avoid the need to make adjustments and possibly contaminate the face or mucous membranes.

In areas where the need for resuscitation is unpredictable, mouthpieces, pocket resuscitation masks with one-way valves, and other ventilation devices provide an alternative to mouth-to-mouth resuscitation, preventing exposure of the caregiver’s nose and mouth to oral and respiratory fluids.

 

Safety precautions during aerosol-generating procedures.

Procedures that can generate small particle aerosols - such as bronchoscopy, endotracheal intubation, open suctioning of the respiratory tract, and dental procedures - have the potential to transmit infectious agents to health care personnel. Protection of the eyes, nose and mouth, in addition to gown and gloves, is recommended while performing these procedures in accordance with Standard Precautions. Use of a particulate respirator is recommended during aerosol-generating procedures when the aerosol is likely to contain M. tuberculosis, SARS-CoV, or avian or pandemic influenza viruses.

 

What work practice controls are effective for reducing exposure to airborne pathogens?  

Rapid identification of suspected cases

Rapid identification of disease will significantly reduce the risk of exposure to others. Clinicians need to be aware of the airborne diseases (e.g., tuberculosis) which are prevalent in their community and be able to recognize the symptoms and identify the populations at risk for such diseases. With the potential use of airborne pathogens as part of bioterrorist activity, it is imperative that health care providers be alert and responsive to patients who may have symptoms of diseases commonly associated with this threat, such as smallpox or anthrax. Rapid identification of airborne disease enables the timely initiation of appropriate therapy and the prompt isolation of patients from all other susceptible individuals. Emergency rooms and clinics

should have triage procedures in place which allow for the identification of infectious patients at the first point of contact with health care personnel.

Isolation of potentially infectious individuals from others at risk.

The patient who is suspected of having an airborne infection should be immediately separated from others at risk. In a hospital setting, the patient should be placed in an isolation room without delay, if an assessment reveals the possibility of an airborne infection (e.g., tuberculosis, chicken pox, measles or smallpox). Diagnostic tests which may confirm the presence of infection should be performed while the patient is isolated.

If transport or movement is necessary, minimize patient dispersal of infectious droplet nuclei by: (1) placing a surgical mask on the patient (if possible) and (2) covering the patient with a linen sheet if a rash is present.

The patient should remain in isolation until either the presence of the disease is ruled out or until the disease has progressed to a non-contagious state. In an ambulatory care setting, the patient should be kept in a room away from others until either the patient is transferred to a hospital (e.g., in the case of tuberculosis), or until the patient is sent home (e.g., in the case of a child with chicken pox).

Cover the mouth when coughing.

The global outbreak of SARS in 2003 emphasized the importance of preventing transmission of respiratory infections at the first point of contact within a health care setting (e.g., reception and triage areas in emergency departments, outpatient clinics, and physician offices).

Respiratory Hygiene / Cough Etiquette was incorporated into Standard Precautions as a practical approach to reducing the risk of airborne transmission of infectious agents such as M. tuberculosis bacilli, as well as pathogens transmitted via large respiratory droplets, such as influenza virus, adenovirus, B. pertussis, N. meningitides and Mycoplasma pneumoniae.

Respiratory hygiene entails educating patients to cover their mouth when coughing or sneezing - one of the most effective ways to control the spread of airborne pathogens. This simple practice reduces the number of airborne bacterial or viral particles, thereby decreasing the risk of transmission to patients and staff in the immediate area.

In common waiting areas, coughing persons should be encouraged to sit at least three feet away from others if feasible.

Covering the mouth when coughing is particularly important when there is a delay in placing the patient into an isolation room. Non-compliant patients should be fitted with a face mask until an isolation room becomes available.

Health care facilities should ensure the availability of materials for adhering to respiratory hygiene in waiting areas for patients and visitors. Tissues should be provided along with a no-touch receptacle for disposal of contaminated tissues.

Patients and visitors should be instructed to perform hand hygiene after contact with respiratory secretions. Dispensers of alcohol-based hand rub should be conveniently located. Where sinks are available, ensure that supplies for hand washing (i.e., soap, disposable towels) are consistently available.

SELECTION AND USE OF PERSONAL PROTECTIVE EQUIPMENT WHICH IS DESIGNED TO PREVENT PATIENT & HEALTH-CARE WORKER CONTACT WITH

POTENTIALLY INFECTIOUS MATERIAL

Introduction           

This section of the course provides information regarding the appropriate use of personal protective equipment in the health care setting as a means of reducing exposure to infectious pathogens.          Upon completion of this module, the learner will be able to:

Recognize circumstances which call for the use of personal protective equipment in order to prevent patient and health care worker contact with potentially infectious material;

Identify specific personal equipment which is used to protect patients and health care workers from exposure to infectious pathogens.

What is Personal Protective Equipment?

Personal protective equipment refers to specialized clothing and equipment worn by health care providers for protection against hazards.

         What types of personal protective equipment are available to health care workers and when should this equipment be used?

There is a wide variety of protective equipment available to health care workers. The selection of equipment for use in a specific situation is based upon the amount of contact the provider will have with a patient's body fluids and/or mucous membranes.

          GLOVES          What types of gloves are available?         Both sterile gloves and non-sterile gloves are available for use by health care workers. 

Sterile surgical gloves are used for performing procedures which involve direct contact with sterile body parts (e.g., surgical operations). Sterile gloves are also used when procedures are performed which require the entry of sterile devices into sterile areas of the patient's body (e.g., cardiac catheterization, indwelling urinary catheter insertion, etc.). The use of sterile gloves is required in order to reduce the risk of infection transmission to the patient.

Non-sterile examination gloves are used for performing procedures which may require contact with a patient's body fluids, mucous membranes, or non-intact skin. Non-sterile utility gloves should be used when decontaminating patient care equipment, when cleaning the patient care environment, or when removing medical waste.

Most gloves made for use in the health care setting are constructed of latex.

Some gloves are made of vinyl or a similar polymer. Utility gloves are generally made of rubber. Nitrile gloves are specifically designed for handling wet instruments which are disinfected with glutaraldehyde solution.

Health care workers should be aware that gloves made of certain materials may cause allergic reactions. If health care workers or patients are allergic to latex, hypo-allergenic gloves should be used instead. Health care providers who are allergic to powder should use powderless gloves.

  

When should gloves be worn?

Gloves should be used whenever there is a potential for contact with a patient's body fluids, mucous membranes, or non-intact skin.

Gloves should be worn while performing blood-drawing procedures and while handling items contaminated with potentially infectious body fluids.

Gloves should be removed as soon as a procedure is completed and hand hygiene should be performed following glove removal. Gloves should always be changed before beginning a procedure on the next patient.

If there is a risk of contact with large quantities of body fluid, two pairs of gloves (double gloving) should be used for additional protection.

Gloves should not be worn unnecessarily for long periods of time. Doing so will increase the health care worker's risk

of infection, as the moist skin inside the gloves creates an environment that is conducive to the growth of bacteria. In addition, disposable gloves may develop small imperceptible holes through which pathogenic organisms may pass.

 What types of cover garb are available?           Cover garb includes the following garments:   

Gowns Aprons Laboratory coats

The choice of appropriate cover garb should be based upon the characteristics of the garments. Cover garb is available in three varieties:

Impervious garments are generally reinforced for additional protection. If an impervious garment becomes saturated with large quantities of body fluid, the fluid will NOT soak through to the skin.

Fluid-resistant garments provide protection against contact with moderate amounts of body fluids. If a fluid-resistant garment becomes saturated with large quantities of body fluid, the fluid CAN soak through to the skin.

Permeable garments provide protection against contact with small amounts of body fluids or small fluid splashes. If a permeable garment becomes saturated with moderate or large quantities of body fluid, the fluid CAN soak through to the skin.  

   When should cover garb be worn?

Cover garb should be used whenever there is a risk that arms, legs, or clothing will become contaminated with a patient's body fluids.         

An impervious gown should be used in situations where there may be exposure to large quantities of body fluid. An impervious gown should be worn in the operating room or while providing emergency care to severe trauma patients.           

A fluid-resistant gown should be used in situations where there may be exposure to lesser quantities of body fluid. A fluid-resistant gown should be worn when removing soiled linen from a bed or when performing procedures (e.g., dental procedures) which may generate significant aerosol fluid spray.

Laboratory coats can be used (in lieu of gowns) in situations where only minimal exposure to body fluids is likely. A laboratory coat can be worn when processing laboratory specimens or drawing blood.

Sterile gowns are used when sterile procedures (e.g., surgical operations) are performed. Sterile gowns must be worn in order to reduce the risk of infection transmission to the patient.

   FACIAL MASKS           What types of masks are available?          Masks available for use by health care providers are classified as follows:

Non-surgical (or procedure) masks are fluid-resistant and have the capacity for relatively high filtration of pathogenic organisms. Non-surgical and surgical masks have the same physical appearance.

Surgical masks are lightweight and generally not fluid-resistant.

Particulate respirators are HEPA filtration masks which can screen out particles less than five microns in size.

When should masks be worn?         Masks can provide two types of protection.

Respiratory protection - masks can protect the healthcare worker from inhaling pathogenic organisms.

Barrier protection - masks can protect the mucous membranes of the mouth and nose from direct contact with a patient's body fluids that may become airborne as a result of accidental splashes or aerosols.

 

  Procedure masks should be worn whenever there is a risk of facial contamination with a patient's body fluid. Facial contamination may occur during the performance of any procedure which generates sprays or aerosols (e.g., dental procedures). Because most procedure masks have a relatively high capacity for filtering most pathogenic organisms, they will provide respiratory protection for the health care provider who is caring for a patient with an infection which may be transmitted by infectious droplets, i.e., a patient on Droplet Precautions.

Surgical masks are lightweight but generally not fluid-resistant. Some surgeons prefer to use surgical masks, in lieu of procedure masks, because they are more comfortable to wear over extended periods of time. Fluid-resistant procedure masks are an appropriate alternative for surgeons who desire maximum personal protection during the performance of surgical procedures.

Particulate respirators are mandated under OSHA regulations for use by all health care employees who enter rooms which house patients with known or suspected pulmonary tuberculosis. Particulate respirators are also recommended for health care workers caring for patients with known or suspected smallpox infection (if an outbreak should occur) and when caring for patients with known or suspected SARS or Avian Influenza A (H5N1).

Particulate Respirators This type of facial protection is officially classified as a "respirator" because it creates an air tight seal on the user's face and provides HEPA filtration of inhaled air. 

Because of the "respirator" designation, there are specific rules and regulations that govern the use of these devices. OSHA requires that health care employees be medically cleared, be provided with specialized training, and be tested for appropriate facial fit before they may use a particulate respirator for the first time.

A complete guide for administering a Respirator Program is available through the National Institutes of Occupational Safety and Health. This document is available on the Course Reference page following completion of this course work.   GOGGLES AND FACE SHIELDS         The need for eye protection is often overlooked by many health care providers. However, it is important to remember that infectious pathogens can enter the body through the eyes, just as they can enter the body through the mucous membranes. For this reason, eye protection is very important when encountering situations in which body fluid splashing may occur.          Goggles are simple and convenient to use. In addition, they provide greater protection than ordinary eyeglasses. This is because goggles are designed with side pieces which cover all points of entry to the eyes, while eyeglasses leave gaps on the sides through which fluids or aerosols may enter.     

Some face masks incorporate a face shield into their design.

These composite devices are convenient to use and offer additional protection for health care workers who perform procedures which are likely to generate body fluid splashing.

Face shields provide full facial protection by means of a transparent shield which extends from the forehead to the area just below the chin.

  SHOE AND HEAD COVERS         Shoe covers are recommended for use when performing procedures (e.g., orthopedic surgeries) in which the health care provider's shoes are likely to become grossly contaminated by the patient's body fluids. Since the risk of pathogen transmission from the surgeon's shoes to the patient is relatively small, shoe covers are not regarded as important infection control barriers. Their use in operating rooms is generally for aesthetic purposes, rather than for scientific ones. In circumstances where there is a likelihood of gross contamination, fluid-resistant boots are a better choice than shoe covers as they provide protection for the entire lower leg.          Head covers protect patients against pathogen transmission from the surgical team members' hair during the course of an operation. Head covers are not regarded as a barrier to infection for health care providers.  

What are some general considerations for the selection and use of personal protective equipment?          Impermeable barriers must be used whenever there is a potential for contact with large quantities of blood or body fluids.           Barriers need not be used in situations where there is only casual patient contact.          Gloves should only be used when there is a potential for contact with body fluids, mucous membranes, non-intact skin, or other contaminated items which may transmit infection.           Sterile barriers must be used when performing surgical procedures or invasive procedures (e.g., the insertion of intravascular monitoring devices).           Barriers should always be changed before beginning work on the next patient.

CREATION AND MAINTENANCE OF A SAFE ENVIRONMENT FOR PATIENT CARE THROUGH THE APPLICATION OF INFECTION CONTROL PRINCIPLES

AND PRACTICES FOR CLEANING, DISINFECTION, AND STERILIZATION

Introduction           

This section of the course provides information regarding the disinfection and sterilization of patient care equipment and the maintenance of the patient care environment.        Upon completion of this module, the learner will be able to:

List several methods of reprocessing patient care equipment which will effectively maintain the integrity of the equipment and assure patient safety;

Define disinfection and sterilization;

Describe differences between high level, intermediate level and low level disinfection and identify circumstances where they are appropriately applied;

Discuss the health care worker's professional responsibility to maintain a safe patient care environment.

The use of contaminated equipment may expose the patient to infectious pathogens.  What factors may contribute to contamination?

Inadequate cleaning.

Inadequate sterilization and disinfection.

Contamination of the disinfectant solution or the rinse solution.

Reuse of disposable equipment.

Failure to reprocess or dispose of equipment before its use on the next patient.

         What is the difference between sterilization and disinfection?

Sterilization is a process which completely eliminates all forms of microbial life.

Disinfection is a process which eliminates many or all pathogenic microorganisms which may be present on an inanimate object, with the exception of bacterial spores.

There are three levels of disinfection:        

High-level disinfection - elimination of all microorganisms, with the exception of large numbers of bacterial spores.

Intermediate-level disinfection - elimination of specific organisms, i.e., Mycobacterium tuberculosis, vegetative bacteria, most viruses, and most fungi. Intermediate-level disinfection does not eliminate bacterial spores.

Low-level disinfection - elimination of most vegetative bacteria, some viruses, and some fungi. Low-level disinfection cannot be relied upon to eliminate resistant microorganisms (e.g., tubercle bacilli, bacterial spores)

     What is the most important element of the sterilization and disinfection process?          Cleaning is the most important step in the sterilization and disinfection process. Cleaning refers to the removal of all foreign material (e.g., soil, organic material) from an object. There are several important points to be made regarding the cleaning process:

The presence of foreign material will protect microbes from exposure to disinfectants and sterilants.

Cleaning should be performed immediately after the item is used to prevent foreign material from drying and adhering to the instrument.

Physical cleaning eliminates large numbers of microbes, thereby increasing the efficiency of the disinfection and sterilization process.

The presence of organic matter may inhibit the ability of disinfectant solution to eliminate microorganisms.

Residual detergent from cleaning may inactivate the disinfectant; therefore rinsing is important.

         Dirt is not sterile. An item cannot be considered sterile if it has body substances encrusted onto it, even if the item has gone through a sterilization process.

  Can the cleaning process be automated?        Automated cleaning will effectively remove foreign material (e.g., organic material, soil) from patient care equipment. In addition, automated cleaning reduces the transmission of potentially infectious body fluids to personnel who are responsible for processing contaminated instruments.Common tools for automated cleaning include:

Washer-sterilizer - mechanically agitates a detergent bath in which an item is immersed. The item is usually put through a steam heat cycle which sterilizes its surface areas.

Ultrasonic cleaner - produces sonic waves which generate minute bubbles from gas nuclei. The bubbles implode, thereby dissolving foreign material from surfaces.

Washer-decontaminators or Washer-disinfectors – act like a dishwasher and use a combination of water circulation and detergent to remove soil. They are very effective in removing and inactivating microorganisms from instruments. Washer-disinfectors are generally computer-controlled units for cleaning, disinfecting, and drying solid and hollow surgical and medical equipment.

How can health care professionals select the appropriate method of sterilization or disinfection for reprocessing specific patient care items?          

There are basic guidelines that can assist health care providers in making decisions regarding the appropriate level of disinfection or sterilization.

Health professionals who are responsible for reprocessing instruments should always consult the manufacturer's guidelines for instructions regarding the proper method of cleaning, disinfection or sterilization. Many instruments, such as endoscopes, are constructed with delicate parts (e.g., camera lenses) which may be damaged by disinfectant solutions or inappropriate sterilization processes.

E.H. Spaulding developed a "rational approach to sterilization and disinfection". According to Spaulding, the appropriate method of sterilization or disinfection becomes clear when patient care items are classified into one of three categories.          1. Critical items

Critical items are instruments or equipment which come into contact with sterile tissue or the vascular system. If they are contaminated with any microorganisms, critical items will pose a high risk of infection to the patient. Therefore, critical items must be kept sterile.

Examples of critical items include the following:

urinary catheters needles and syringes orthopedic implants cardiac catheters scalpels surgical instruments

Single-use disposable sterile items must be stored in a manner to maintain integrity of the manufacturer’s packaging. Non-disposable items (e.g., surgical instruments) must be cleaned and undergo appropriate sterilization before they can be re-used. 

 2. Semi-critical items

Semi-critical items are instruments or equipment which come into contact with mucous membranes or with non-intact skin. These items must be kept free of all microorganisms except for small numbers of bacterial spores.

Since the body's mucous membranes can resist infection from small numbers of bacterial spores, their presence does not pose a risk of infection.

Semi-critical items generally require high-level disinfection.

Examples of semi-critical items include the following:

respiratory therapy equipment anesthesia equipment endoscopes

3. Non-critical items

Non-critical items refer to equipment which comes into contact with intact skin but not with mucous membranes. Since intact skin acts as an effective barrier to most microorganisms, sterility is not critical. Intermediate-level and low-level disinfection of non-critical items is acceptable.

Examples of noncritical items include the following:

blood pressure cuffs

crutches patient furniture

 

Table 5-1: Infection-control categories of patient-care instruments used in the practice of Dentistry 

Category Definition Dental instrument or item

Critical

Penetrates soft tissue, contacts bone, enters into or contacts the bloodstream or other normally sterile tissue.

Surgical instruments, periodontal scalers, scalpel blades, surgical dental burs

Semicritical

Contacts mucous membranes or nonintact skin; will not penetrate soft tissue, contact bone, enter into or contact the bloodstream or other normally sterile tissue.

Dental mouth mirror, amalgam condenser, reusable dental impression trays, dental handpieces. Although dental handpieces are considered a semicritical item, they should always be heat-sterilized between uses and not high level disinfected.

Noncritical Contacts intact skin.Radiograph head/cone, blood pressure cuff, facebow, pulse oximeter.

Noncritical clinical contact surfaces

Surfaces touched frequently with gloved hands during patient care.

Light handles, switches, dental x-ray equipment, chair-side computers. Barrier coverings (e.g plastic wrap) should be placed on surfaces and changed between patients. If not covered, surfaces should be disinfected between patients.

 What are the most common methods of sterilization utilized in a health care setting?      

Steam under pressure is the preferred method for sterilizing for instruments that are stable in the presence of heat and moisture such as stainless steel surgical instruments.

Ethylene oxide, hydrogen peroxide gas plasma and ozone are appropriate for devices that may be damaged by heat and moisture, such as cameras and lensed instruments.

Liquid chemicals – i.e., peracetic acid, high-concentration hydrogen peroxide, and glutaraldehyde – are appropriate for devices that can tolerate moisture but not high temperatures.

Dry heat is appropriate for sterilization of anhydrous oils, petrolatum products, and powders; however, since the majority of these products are provided sterile by commercial manufacturers, dry heat is rarely used in medical facilities.

For those health professionals who have direct or indirect involvement in instrument processing, it is recommended that Table 5-2 be closely reviewed.

The following table provides detailed information about methods of sterilization:

Table 5-2: Methods of Sterilization

  

METHOD OF STERILIZATION

HOW IT WORKS

TYPEADVANTAGES AND DISADVANTAGES

Steam sterilization

Saturated steam is produced under pressure. Temperatures must reach a specific level in order to ensure the elimination of microorganisms. Items are exposed for specified periods of time at 100% relative humidity

Variety of sizes ranging from small tabletop models to large chamber sterilizers. Gravity sterilizer. High-speed vacuum sterilizer.

Advantages: highly effective; rapid heating and penetration of textiles and device lumens; low cost; non-toxic.

Disadvantages: items must be heat and moisture-resistant.

Hydrogen Peroxide Gas

Plasma

Gas plasma is created in a vacuum chamber through the combination of radio waves and hydrogen peroxide vapor. This combination generates reactive free radicals which eliminate all microorganisms, including spores.

Hydrogen peroxide-gas plasma system (marketed as STERRAD 200).

This system is manufactured by Advanced Sterilization Products, a division of Johnson & Johnson.

Advantages: highly sporicidal; environmentally safe and easy to use; compatible with most medical devices; fast cycle time.

Disadvantages: special packing material required – cellulose paper, linens & liquids cannot be processed; reduced efficacy in the presence of foreign material; inability to enter into very small and long lumens.

Liquid peracetic acid

sterilizer

Instruments are submerged in 0.2% peracetic acid liquid within a computer-directed processing unit. Connectors direct fluid through the lumens of endoscopes.

Steris System.

This system is manufactured by Steris Corporation.

Advantages: rapid cycle; low temperature; fully automated; environmentally friendly; safe to use; penetrates lumens of endoscopes.

Disadvantages: for immersible items only; affected by organic matter; for point of use only - no sterile storage.

Ethylene Oxide gas

A chamber is filled with the proper concentration of Ethylene oxide gas,

Use of ETO sterilization is limited to facilities that comply with EPA standards

Advantages: very effective method of sterilization – penetrates packaging and lumens; safe for heat

under optimum temperature and humidity. The gas eliminates microorganisms by inhibiting their metabolism.

for safe exhaust of gas.

sensitive items.

Disadvantages: very toxic to personnel and patients, and is harmful to the environment; rooms housing ETO sterilization chambers require special aeration; flammable and explosive; long cycle time; requires aeration.

Ozone

Under vacuum, water vaporizes at room temperature. Oxygen is subjected to an electrical discharge, breaks down into monatomic oxygen and then re-forms as ozone (O3). Contents are sterilized through oxidation. Ozone then reverts to oxygen and is vented into the room along with low humidity water vapor.

Ozone gas sterilization Advantages: safe to use and environmentally friendly; non-corrosive to metals and effective for reprocessing of metals, glass, ceramics, silica, plastics and elastomers; no aeration time or cool-down time is required; requires only appropriate steam and water quality, oxygen gas and electricity.

Disadvantages: limited use -- the system is not intended for use in processing any flexible endoscopes, glass or plastic ampoules, liquids or implants; small chamber.

Dry heat sterilization

Instruments are exposed to temperatures ranging from 121 degrees C to 171 degrees C for specified periods of time.

Gravity convection.Mechanical convection.

Advantages: non-corrosive; low cost; suitable for powders and glass.

Disadvantages: uneven penetration; long exposure times may be required; high temperatures are not suitable for rubber goods and some fabrics.

Other Liquid Chemicals

Instruments are submerged in sterilant solutions for specified periods of time, as recommended by the manufacturer.

Hydrogen Peroxide 7.5%; Glutaraldehyde 2%;Peracetic acid 0.2%; etc.

To be discussed in detail in the section on disinfection.

 

How is the sterilization process monitored to assure adequate processing of instruments?

Monitoring the sterilization process is a key element in patient safety. The process assures that pathogens are being removed from medical devices and allows early detection of failures in the sterilization process so that medical devices can be promptly removed from circulation and reprocessed before being used on a patient.

The sterilization process is routinely monitored by mechanical, chemical and biological indicators.

Mechanical parameters - such as temperature, pressure and cycle time - are monitored through instrument gauges and charted to assure that the physical parameters required for sterilization are achieved.

Chemical indicators are paper strips, tape or labels composed of heat or chemical sensitive inks. These indicators are placed inside and outside of packages of instruments undergoing sterilization and will change color when the item has been sufficiently exposed to one or more of the parameters of the sterilization process. Chemical indicators are not a guarantee that an item is sterile; they indicate only that the item has been exposed to one or more of the parameters.

Biological indicators determine the efficacy of the sterilization process. A biological indicator is configured as a strip, capsule, or ampoule that contains at least a million known living and highly resistant spores. If the spores are killed during the sterilization process, it can be inferred that the process was effective and the item is sterile.

For those practitioners who have direct or indirect involvement in instrument processing, it is recommended that Table 5-3 be carefully reviewed.

       The following table describes recommended methods for monitoring the sterilization

process:         

Table 5-3: Monitoring the Sterilization Process

    

METHOD OF STERILIZATION

REQUIRED MONITORING PROCESS

Steam

Mechanical indicators: maintain charts which record time and temperature; pressure gauge readings. Required with every load.

Chemical indicators: paper strips which change color when exposed to proper time, temperature, and humidity. Required with every load. Strips should be placed on the inside and the outside of each pack.

Biological indicators: Geobacillus stearothermophilus spore testing. Recommended weekly and with any load which contains implantable devices.

Hydrogen Peroxide

Gas Plasma

Mechanical indicators: maintain charts which record time and temperature; pressure gauge readings. Required with every load.

Biological indicators: Geobacillus stearothermophilus spore testing.

Ozone

Mechanical indicators: maintain charts which record time and temperature; pressure gauge readings. Required with every load.

Chemical indicators: specific to ozone gas.

Biological indicators: Geobacillus stearothermophilus spore testing.

Liquid Peracetic

Acid

Process monitoring is performed by the instrument's computer (Steris System). Required with every load.

Biological indicators: Geobacillus stearothermophilus spore testing.

Ethylene Oxide Gas

Mechanical indicators: maintain charts which record time and temperature; pressure gauge readings. Required with every load.

Chemical indicators: paper strips which change color when exposed to proper time, temperature, and humidity. Required with every load. Strips should be placed on the inside and the outside of each pack.

Biological indicators: Bacillus atrophaeus  spore testing. Recommended weekly and with any load which contains implantable devices.

Other Liquid Chemicals

In general, use chemical test strips to assure the proper concentration of liquid chemicals. Consult the manufacturer's guidelines.

Dry Heat

Mechanical indicators: maintain charts which record time and temperature. Required with every load.

Biological indicators: Bacillus atrophaeus  spore testing. Recommended weekly.

  Instruments that are being prepared for sterilization must be scrupulously cleaned and appropriately wrapped and packaged prior to and/or after undergoing sterilization. The sterilizer’s manufacturer should be consulted regarding the appropriate packaging materials to use. Liquid chemical sterilization does not allow for the pre-packaging of items. Hence, great care must be taken following the sterilization process to ensure that instruments do not become re-contaminated.

How should sterile items be stored?

Sterile items should be stored in closed cabinets in a limited access area. The area should be clean, dry, and dust-free with a temperature of 65 - 72 degrees F and a relative humidity of 35 - 50%. Packages should be kept on clean shelves that are 8 - 10 inches above the floor, 18 - 20 inches below the ceiling, and 6 - 8 inches from the wall.

How long will instruments remain sterile following adequate re-processing?

Event-Related Sterility is a practice currently recommended by numerous professional associations including the Association of Operating Room Nurses. If an instrument is stringently re-processed, it will remain sterile until some event causes the item to become contaminated (e.g., tear in the packaging, packaging becoming wet, etc). Packages should be closely inspected, prior to opening, to ensure that integrity has remained intact. Instruments should not be used if there is any evidence of damage to the packaging. Expiration dates are only needed to ensure proper inventory turnover or to indicate expiration of some component of the pack (e.g., skin preparation solution).

What are the most common methods of disinfection?           Semi-critical patient care items require high level disinfection which is most commonly achieved through the use of liquid chemicals. Pasteurization (i.e., high level disinfection with hot water) may be used to disinfect equipment which can tolerate heat and water such as anesthesia equipment and respiratory therapy equipment.

The most common high level disinfectant solutions available today are:

Glutaraldehyde: 2% or greater concentration Ortho-phtalaldehyde: 0.55% concentration Hydrogen peroxide: 7.5% concentration Combined hydrogen peroxide and peracetic acid in various concentrations Hypochlorite (free chlorine) in a concentration of 650-675 ppm

Some of these chemical solutions can also be used to achieve sterilization. The chemical’s product label is the best place to find information regarding the appropriate soak time and temperature necessary to achieve high level disinfection or sterilization. It will also provide a listing of the infectious pathogens against which the chemical is active.  Before soaking instruments in these chemicals, the instruments must be scrupulously cleaned in order to remove all organic matter.

For those practitioners involved directly or indirectly with reprocessing instruments used on patients, the following table provides information regarding the advantages and disadvantages of the various liquid chemicals available to achieve high level disinfection / sterilization:

 

The following table provides information regarding the advantages and disadvantages of using liquid chemicals to achieve high-level disinfection / sterilization:

         Table 5-4: High-Level Disinfection / Sterilization

  

CHEMICAL ADVANTAGES DISADVANTAGES

Peracetic Acid  

Environmentally friendly & safe for personnel.Rapid action in low concentration.Effective in the presence of organic matter.Rapidly sporicidal.

Oxidizing agent may be corrosive.

Immersible instruments only.

Unstable, particularly if diluted.

Hydrogen Peroxide

 

No activation required.May enhance removal of organic material.Environmentally friendly - decomposes into hydrogen and water.No odor or irritation issues. 

Material compatibility issues - oxidizing properties may be harmful to scopes.Copious rinsing required.Serious eye damage with contact.

Combination Peracetic Acid /

Hydrogen Peroxide

No activation required. Insignificant odor and irritation.

Oxidizing agent may be corrosive.Contact with eyes or skin may be damaging.

Glutaraldehyde

Relatively inexpensiveExcellent materials compatibility including compatibility with lensed instruments

Toxic and caustic to skin.Copious rinsing required.Pungent and irritating fumes - special ventilation required.Coagulates blood and fixes tissues to surfaces.Relatively slow mycobactericidal activity.

Ortho- phthalaldehyde

(OPA)

 

Rapid high level disinfection.Does not require activation.Weak odor.Excellent materials compatibility

May stain skin, mucous membranes, clothing and environmental surfaces. High cost.Slow sporicidal activity.

   These solutions must be routinely monitored with manufacturer-specific test strips to assure that the chemical solution is at the proper concentration to achieve high level disinfection or sterilization. If a test strip determines sub-optimal concentration, the solution must be discarded. In addition, these solutions have very specific expiration dates and must be discarded when expired. A solution at sub-optimal concentration must be discarded regardless of expiration date.

In general, when using any chemical disinfectant:

Read the label for activity and use instructions.

All items must be thoroughly cleaned before disinfecting.

All items must be thoroughly rinsed and dried after disinfecting. Care must be taken to avoid re-contaminating items.

Only surfaces in direct contact with the solution will be disinfected. Instruments must be opened, disassembled, and completely submerged for the required period of time in order to achieve disinfection.

Items should be dry before submerging to avoid diluting the solution to inactive levels.

Gloves should be worn to protect the skin. The use of goggles may be advisable to protect the eyes from fluid splashes.

 

What disinfectants are appropriate for non-critical patient equipment and sanitizing the patient care environment?

Intermediate and low level disinfection is appropriate for non-critical patient care equipment and for sanitizing the patient care environment. The chemical’s product label should be consulted for specific instructions regarding proper use. The product label will also identify the specific pathogens which will be eliminated by the chemical.

      

The following table provides detailed information about the use of chemicals for intermediate and low-level disinfection:  

      Table 5-5: Intermediate and Low-Level Disinfection

  

CHEMICAL CONSIDERATIONS TYPICAL USES

Alcohol: Isopropyl 70%

Requires wet contact for at least

five minutes to achieve a

reasonable level of disinfection.

Evaporation may alter

concentration and diminish activity.

Volatile; flammable.

Inactivated by organic matter.

Damaging to lensed instruments.

Disinfection of thermometers.

Disinfection of external surfaces of

equipment such as stethoscopes.

Skin antiseptic.

Rubber stoppers of medication vials.

Chlorine Sodium Hypochlorite

(Bleach)

Must be diluted with water to be

effective.

Corrosive to metals.

Can not generally be combined with

detergents.

Inactivated by organic matter.

Tonometer heads.

Disinfection of hydrotherapy tanks,

renal dialysis equipment, and CPR

training mannequins.

Disinfection of toilets, bathtubs.

Dental equipment.

Decontamination of blood spills.

Laundry.

Sanitizer for dishwashing.

Iodophors (Iodine-based

solutions)

Relatively free of toxicity and

irritancy.

Powerful detergent action.

May stain fabrics, plastics, and

synthetics.

Inactivated by organic material.

Disinfection of thermometers,

hydrotherapy tanks.

Note: antiseptic iodophor solutions

(e.g., Povidone Iodine, Betadine)

are not suitable for use as hard-

surface disinfectants.

Quaternary Ammonium Compounds

Good detergency properties.

Good germicidal properties.

Affected by organic material.

Housekeeping programs for walls,

floors, and furnishings.

Phenolic Solutions

Leaves a residual film on

environmental surfaces.

May cause skin irritation.

Affected by organic material.

Corrosive to rubber and certain

plastics.

Not to be used in the Nursery.

Housekeeping programs for walls,

floors, and furnishings.

Accessory patient equipment.

  Non-critical patient care equipment should be cleaned with an appropriate disinfectant solution which remains in contact with the item for at least 1 minute. Any non-critical equipment that is used in the care of a patient on Contact Precautions should be disinfected before being used on another patient.

Are there any special considerations for disinfection with emerging pathogens like MRSA or Clostridium difficile?

The standard sterilization and disinfection practices covered in this element are adequate to process instruments or devices contaminated with blood and other body fluids from persons infected with emerging pathogens.

In instances where clusters of patients are found to be infected with Clostridium difficile or norovirus, environmental surfaces should be cleaned with a disinfectant known to be active against these agents – e.g., hypochlorite (bleach) solution in a 1:10 dilution. The manufacturer’s label on the container of the disinfectant solution will contain specific information regarding pathogens against which the chemical content is active.

With the advent of computerization in health care settings, computer keyboards used by multiple staff members have the ability to become a potential object of “touch” contamination in patient areas. Keyboards should be disinfected daily for 5 seconds and when visibly soiled. One study showed that commercial disinfecting wipes (Clorox and Metrex) were effective at removing 95% of bacteria from the keyboard (without any cosmetic damage after 300 wipes) and had a residual anti-bacterial effect for 48 hours.

 

Glucose monitoring devices or glucometers are commonly used in many inpatient and outpatient settings. In 2005, the Centers for Disease Control reported the findings of three outbreaks of Hepatitis B virus (HBV) among patients in long term care facilities. Transmission of the virus was associated with contaminated glucose monitoring devices. Patients should be assigned separate glucometers. If a glucometer is to be used on another patient, the exterior surface of the device should be disinfected with a solution that is capable of eliminating HIV and HBV virus and is active against tuberculosis, or a dilute solution of bleach (1:10 – 1:100 concentration). Alcohol is not recommended as it will damage the LED readout of the glucometer and quarternary ammonium solutions may damage metal parts. Single use lancets that permanently retract upon piercing the skin are preferred.

 

The United States Environmental Protection Agency maintains an online listing of registered antimicrobial products effective against certain blood borne/body fluid pathogens, Mycobacteria tuberculosis (tubercle bacteria), human HIV-1 virus, Hepatitis B, Hepatitis C viruses, as well as products classified as sterilizers. There are also products registered as effective against Methicillin Resistant Staphylococcus aureus (MRSA), Vancomycin Resistant Enterococcus faecalis or faecium (VRE), human Norovirus (Norwalk like Virus), as well as products used for medical waste treatments in health care/medical facilities. The EPA website is www.epa.gov.

 

Can an item that is labeled “Single Use Only” be reused?

Reuse of a device that is labeled for single use should never be considered casually. This practice may increase risk of harm to the patient and may result in legal liability for the health care provider and/or the health care facility.

On October 26, 2002, the Medical Device User Fee and Modernization Act of 2002 (MDUFMA), P.L. 107-250, was signed into law. This law provided new regulatory requirements

for reprocessing of single-use devices. According to this new provision, any entity reprocessing a single-use device must perform a scientific study to provide validation data demonstrating that the safety and integrity of the reprocessed device is substantially equivalent to the predicate device. In August, 2006, the regulation was amended to state that any reprocessed single-use device must be conspicuously labeled with the name, abbreviation, or symbol of the reprocessor.

There are independent enterprises which provide services to health care providers or health facilities that wish to re-process or re-sterilize certain single use items. These companies will assume legal responsibility for the integrity of the item. Health facility administrators who wish to pursue this option should consult with legal counsel, risk management, infection control, and their liability insurance carrier before contracting for this service.

Do guidelines on sterilization and disinfection exist for special circumstances?

Many professional organizations publish important guidelines with information pertinent to disinfection and sterilization of specialized patient care equipment, e.g., dental equipment, endoscopy equipment. In addition, specific guidelines exist for reprocessing patient care equipment when there is a concern of contamination with “prions” - material capable of transmitting Creutzfeld-Jakob disease (or transmissible spongiform encephalopathy diseases like “mad cow disease”).

Health care professionals should equip themselves with the information and resources necessary to maintain a safe environment for delivery of patient care.

The Internet can serve as an excellent resource for locating this type of information. The Centers for Disease Control, Division of Health care Quality Promotion has many publications available on their website:

http://www.cdc.gov/ncidod/dhqp/sterile.html

Please consult the resources associated with this element for more information.

PREVENTING AND CONTROLLING INFECTIOUS AND COMMUNICABLE DISEASES IN HEALTH CARE WORKERS

Introduction           

This section of the course presents strategies for assessing, preventing, and controlling infections and communicable diseases in health care workers.

Upon completion of this module, the learner will be able to:

Recognize the importance of occupational health strategies which are designed to protect both health care workers and patients;

Identify occupational health strategies for preventing the transmission of bloodborne pathogens and other communicable diseases in health care settings;

Recognize non-specific disease findings which should prompt evaluation of health care workers;

Describe approaches to post-exposure management of health care workers who have been exposed to HIV, Hepatitis C Virus or Hepatitis B Virus.

Why are occupational health strategies so important?         Occupational health guidelines and regulations are intended to:

protect health care workers from acquiring infectious or communicable diseases; prevent disease transmission by health care workers to patients and other employees.

Which immunizations are strongly recommended for health care workers?         Measles, Mumps, Rubella (MMR): All persons who work in health care facilities are required to be immune to measles and rubella according to New York State regulations. It is also recommended that the worker be immune to mumps. Health care workers can undergo laboratory testing to verify immunity or provide documentation evidencing prior vaccination for these diseases.

Diphtheria, Pertussis, Tetanus: It is recommended that all health care workers be vaccinated with one dose of Tdap (tetanus toxoid, reduced diphtheria toxoid and acellular pertussis) to protect themselves, their patients, other health care staff, family members and the community against tetanus, diphtheria, and pertussis. After initial vaccination, adults require a tetanus booster shot (0.5 ml) every ten years to ensure immunity. Health care personnel who have direct patient contact should receive a single dose of Tdap vaccine in lieu of the standard tetanus and diphtheria (Td) booster and can do so as little as two years after their last Td shot.

Hepatitis B Vaccine: Any person who performs tasks involving contact with blood, blood-contaminated body fluids, or sharps should be vaccinated against hepatitis B. According to the OSHA Bloodborne Pathogen Standard, employers are required to offer Hepatitis B vaccine, at no charge, to health care workers who are at risk for occupational exposure to blood or body fluids that contain blood. If vaccination is refused, employees are required to sign a statement confirming their understanding of the potential consequences. Such employees may still request vaccination at a future date during their employment.

Influenza Vaccine: Influenza can be a severely debilitating and sometimes deadly disease. The standard of care in New York State is that all health care workers should receive an annual influenza vaccination. In addition, Public Health Law Article 21A, the Long-term Care Resident and Employee Immunization Act, requires that all long-term care facilities, adult homes, adult day health care facilities, and enriched housing programs offer influenza vaccine to all employees and residents. It is generally offered free of charge to employees at large health facilities. If not provided by the employer, influenza vaccine may be obtained at little expense.

Varicella Vaccine: It is recommended that all health care workers be immune to varicella. Evidence of immunity includes documentation of 2 doses of varicella vaccine given at least 28 days apart; a document evidencing history of varicella disease (chickenpox) or herpes zoster based on physician diagnosis; or laboratory documentation showing immunity or confirmation of disease.

The references associated with this module will provide additional information on vaccination requirements for health care workers. These references will be available on the Course Reference page accessible from your Student Control Panel following completion of this course.

    For which diseases should prophylaxis be considered if a health care worker is exposed?

For certain diseases, there is post-exposure prophylactic treatment available to prevent the development of fully symptomatic disease.

The following table provides detailed information regarding the available treatments for specific diseases:

DISEASE EXPOSURE TREATMENT

DiphtheriaContact with the respiratory secretions of an infected person.

Penicillin.Erythromycin.Tdap vaccine.

Hepatitis A Contact with infected feces. Immune globulin within 2 weeks of exposure.

Hepatitis B

Contact with infected blood or body fluids containing blood, via needlestick; splash to the mucous membranes or to the eye; contamination of non-intact skin.

Hepatitis B Immune Globulin.Hepatitis B Vaccine.(To be discussed in detail.)

Meningococcal Meningitis

Intimate exposure to the respiratory secretions of an infected person.

Rifampin.Ceftriaxone.Ciprofloxacin.

Pertussis Exposure to respiratory secretions.Azithromycin.Erythromycin.Trimethoprim-sulfamethoxazole.

Rabies Exposure to infected secretions.Human Rabies Immune Globulin.Human Rabies Vaccine.

Varicella

Exposure to an infected person with a rash or exposure to an infected person for up to two days prior to the development of a rash.

Varicella Immune Globulin forimmunocompromised persons.

HIV

Contact with infected blood or body fluids containing blood, via needlestick; splash to the mucous membranes or to the eye; contamination of non-intact skin.

To be discussed in detail.

TuberculosisGenerally prolonged exposure to a person capable of transmitting bacteria through the air.

Isoniazid for PPD conversion. See resource list for more information re: exposure to drug resistant bacteria.

How do threats of bioterrorism affect health care practitioners?

As part of a national plan to protect Americans from the threat of smallpox, the Department of Health and Human Services (HHS) worked with state and local governments to form volunteer Smallpox Response Teams that can provide critical services to Americans in the event of a smallpox attack. To ensure that Smallpox Response Teams can mobilize immediately in an emergency, health care workers and other critical personnel were asked to volunteer to receive the smallpox vaccine.

As part of this effort, smallpox vaccine was administered to 39,213 volunteer civilian health-care and public health workers in 55 jurisdictions to prepare the United States for a possible terrorist attack using smallpox virus.

The New York City Department of Health and Mental Hygiene (DOHMH) began voluntary smallpox vaccination in January 2003, to establish a "strategic reserve of health and public health response teams." The vaccine was made available to staff in each of approximately 70 acute-care hospitals in New York City and to selected staff at the Department of Health and Mental Hygiene. Vaccination was voluntary. Volunteers are expected to assist in the response effort if a smallpox outbreak were to occur in New York City.

In August, 2005, the New York City DOHMH began recruitment of health professionals who live and work in New York City to its Medical Reserve Corp (MRC). This unit consists of trained volunteer clinicians who are willing to be part of the city's emergency response team in the event of a public health emergency. Registration with the MRC is a "good faith" agreement whereby volunteers agree to report during an emergency if they have satisfied other emergency commitments, including to their hospitals, private practices and families. More information about this program can be found at: www.medicalreserve.org.

All health care providers should immediately report to the Department of Health any suspected or confirmed illness caused by a potential biological threat agent (e.g., anthrax, smallpox, tularemia or plague) or other disease of urgent public health concern (e.g., avian influenza or SARS).

  Which basic practices can health care workers employ to reduce their risk of exposure to infectious diseases?

As previously discussed (see Element II), adherence to Standard Precautions will protect health care personnel from most communicable diseases. In addition, thorough hand cleansing, both before and after patient care, will reduce the risk of acquiring and transmitting infectious disease.

Employers should assure the prompt evaluation of all health care workers who are symptomatic for a potentially infectious disease. Such symptoms include fever, cough, skin rash, draining wounds, vomiting or diarrhea. Employees who may be capable of transmitting infectious disease should be furloughed until their disease has progressed to a non-contagious state.

In the event of an influenza pandemic, employers will play a key role in limiting the spread of infection and protecting employees' health and safety by enforcing appropriate infection control measures such as good hygiene, cough etiquette, and the use of personal protective equipment. Administrators must develop policies that encourage ill employees to stay at home without fear of any reprisals.

Screening programs are useful for identifying employees who may be at risk of acquiring and developing infections. Tuberculosis screening is of particular importance. A PPD skin testing program should be implemented to assess employees who may be exposed to patients with pulmonary tuberculosis. A two-step skin test to establish baseline status is recommended for those employees (e.g., new employees) for whom PPD history is unknown. In addition, conversion rates of employees should be monitored at least once a year. High-risk employees should be monitored more frequently.

Several resources which provide guidelines for prevention and management of occupational exposure to tuberculosis may be found in the CDC web site at: http://www.cdc.gov/tb/default.htm

Comprehensive resources addressing issues related to pandemic flu may be found at:http://www.pandemicflu.gov

  Which occupational health strategies must be implemented in order to protect health care workers from exposure to blood borne pathogens?

Occupational exposure to blood carries a risk of transmission of Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), and Hepatitis C Virus (HCV).

Exposure to each of these viruses can occur through:

percutaneous injury (e.g., needlesticks or cuts from contaminated sharp instruments); blood/body fluid splashes to the eyes, nose, or mouth; blood/body fluid contamination of non-intact skin.

In accordance with OSHA regulations, employers must provide health care workers with:

appropriate protective devices to reduce the risk of exposure; education on practices which are designed to reduce the risk of exposure;

immediate access to treatment should an injury occur; free Hepatitis B immunization to employees who may have occupational contact with

blood or body fluids.

OSHA also requires that employers:

eliminate the use of needles where safe and effective alternatives are available; implement the use of devices with safety features; solicit input from non-managerial employees responsible for direct patient care regarding

the identification, evaluation, and selection of effective engineering controls, including safer medical devices;

maintain records of occupational injuries and illnesses; maintain and provide regular updates to a comprehensive exposure control plan.

What should you do if you are exposed to the blood of a patient?

Needlesticks and cuts should be immediately washed with soap and water.

Splashes to the nose, mouth, and skin should be flushed with clean water.

Eyes should be irrigated with clean water, saline, or sterile irrigants.

Report for immediate evaluation and treatment.

  What are the current recommendations for post-exposure treatment for Hepatitis B and Hepatitis C?         Hepatitis C (HCV)

Hepatitis C virus (HCV) is not transmitted efficiently through occupational exposure to blood. The risk of seroconversion (positive HCV antibody test) following accidental percutaneous exposure to a known HCV-positive source is 1.8%. There have been no documented cases of transmission to a health care worker following intact or non-intact skin exposures to blood.

There is currently no recommended post-exposure prophylactic treatment for Hepatitis C. Following health care worker exposure, the source patient should be tested for Hepatitis C antibodies (anti-HCV). The exposed worker should receive baseline testing for Hepatitis C antibodies (anti-HCV) and alanine aminotransferase levels (ALT).

If the source patient is found to have Hepatitis C antibodies, there is a risk of HCV transmission to the exposed health care worker. The mean incubation period from transmission of HCV infection to the onset of symptoms is 6-7 weeks (range: 2-26 weeks); however, only 20-30% of newly infected persons are symptomatic. Serum ALT levels increase 4-12 weeks after acute HCV infection. Antibodies to HCV (anti-HCV) may or may not be present when symptoms develop or with elevations in ALT levels; however, after 3 months of HCV infection, anti-HCV is detectable by immunoassay in 90% of infected persons. An exposed worker should receive follow-up testing which may include: (1) nucleic acid test for HCV RNA immediately after exposure, at week 4 and at week 12; (2) anti-HCV by EIA or CIA immediately after exposure

and at week 12; and (3) serum ALT and AST immediately after exposure, at week 4 and at week 12.

When HCV infection is identified early, the health care worker should be referred for medical management to a specialist knowledgeable in this area.

There have been substantial improvements in the success of HCV treatment and there are currently several treatments approved by the FDA. Combination therapy, using pegylated interferon and ribavirin, is currently the treatment of choice. Combination therapy can eliminate the virus in about 5 out of 10 persons for genotype 1 (predominant in the U.S.) and in up to 8 out of 10 persons for genotype 2 and 3.

Hepatitis B (HBV)

The risk of Hepatitis B transmission is correlated with both the degree of contact with blood and the hepatitis B "e" antigen (HBeAg) status of the source person. In studies of susceptible health care personnel who sustained injuries from needles contaminated with blood containing HBV, the risk of developing clinical hepatitis was 22% - 31% if the source blood was positive for HBeAg. By comparison, the risk of developing clinical hepatitis was only 1% - 6% if HBeAg was negative.

Percutaneous injuries, such as needle sticks, are among the most efficient modes of HBV transmission. However, these types of exposures only account for a minority of HBV infections among health care workers. Research has shown that most infected health care personnel do not recall an overt exposure such as a percutaneous injury. Also, it is important to recognize that HBV has been demonstrated to survive in dried blood at room temperature on environmental surfaces for at least one week. Thus, HBV infections that occur in persons with no history of exposure may result from contact with contaminated environmental surfaces.

Unlike Hepatitis C, there are recommended prophylactic treatments available to health care workers who may have been exposed to Hepatitis B (i.e., Immune Globulin, vaccine).

The Centers for Disease Control (CDC) has published recommendations for post-exposure evaluation and treatment of health care workers following potential exposure to Hepatitis B which are summarized in the following table:

 

The following table summarizes CDC recommendations for post-exposure prophylaxis for Hepatitis B:

         Table 6-2: Recommended Post-exposure Prophylaxis for Hepatitis B

EXPOSED SOURCE PATIENT IS TESTED AND FOUND TO BE:

PERSONHBsAg Positive HBsAg

NegativeUnknown or Not

tested

Unvaccinated

Administer HB Immune Globulin (HBIG) x 1 dose and initiate HB vaccine series.

Initiate HB vaccine series.

Initiate HB vaccine series.

Previously vaccinated: Known

responder* No treatment. No treatment. No treatment.

Previously vaccinated: Known

non-responder**

HBIG x 2 doses or HBIG x 1 dose, and initiate

revaccination.***

No treatment.

If known high-risk source, may treat as if source were HBsAg Positive.

Previously vaccinated: Response unknown

Test exposed person for Anti-HBs:

If adequate, no treatment;

If inadequate, HBIG x 1 dose, plus HB vaccine booster dose.

No treatment.

Test exposed person for anti-HBs:

If adequate, no treatment;

If inadequate, administer vaccine booster and recheck titer in 1-2 months.

* Responder is defined as a person with adequate levels of serum antibody to Hepatitis B antigen (i.e., anti-HBs >/= 10 mIU/mL)

** Non-responder is defined as a person with inadequate levels of serum antibody to Hepatitis B antigen (i.e., anti-HBs < 10 mIU/mL)

***The option of giving one dose HBIG and reinitiating the vaccine series is preferred for non-responders who have not completed a second 3-dose vaccine series. For persons who previously completed a second vaccine series but failed to respond, two doses of HBIG are preferred.

 

What is the risk of acquiring HIV infection following exposure to known HIV-infected blood?         The risk of acquiring HIV, following occupational exposure, is currently estimated as follows:

Exposure from needlestick or cut - Risk is 0.3% (approximately 1 in 300). Exposure to eye, nose, or mouth - Risk is 0.09% (approximately 1 in 1,000). Exposure to non-intact skin - Risk is less than 1 in 1,000

Risk may be increased if:

Exposure involved a deep injury to the health care worker. Blood is visible on the device which caused the injury. The device had been placed in the source patient's vein or artery. The source patient is in the terminal stages of AIDS.

What are the current recommendations for post-exposure prophylaxis for HIV?

The Centers for Disease Control and Prevention maintains a comprehensive set of guidelines for post-exposure management of occupational exposures to HIV. These guidelines were last updated in September, 2005, and are widely practiced throughout the United States. The New York State Department of Health AIDS Institute, in cooperation with the Johns Hopkins University Division of Infectious Diseases, has developed a modified set of guidelines for statewide implementation which represent a more aggressive approach to blocking HIV infection following occupational exposure. The post-exposure treatment specified in the New York State guidelines is known as HAART – highly active antiretroviral therapy – and consists of a three drug regimen. The post-exposure regimens recommended by the CDC consist of two drugs (basic) or three or more drugs (expanded) depending on the type and severity of exposure sustained by the health care worker.

General considerations following an exposure are as follows:

Wound and skin sites should be cleansed with soap and water immediately. Exposed mucous membranes should be flushed with water.

Post-exposure prophylaxis (PEP) is recommended for exposure to blood or visibly bloody fluid or other potentially infectious material (e.g., semen, vaginal secretions, and cerebrospinal, synovial, pleural, peritoneal, pericardial, and amniotic fluids) associated with potential HIV transmission and in any of the following exposure situations:

Break in the skin by a sharp object (including both hollow-bore and cutting needles or broken glassware) that is contaminated with blood, visibly bloody fluid, or other potentially infectious material, or that has been in the source patient’s blood vessel.

Bite from an HIV-infected patient with visible bleeding in the mouth that causes bleeding in the health care worker.

Splash of blood, visibly bloody fluid, or other potentially infectious material to a mucosal surface (mouth, nose, or eyes).

A non-intact skin (e.g., dermatitis, chapped skin, abrasion, or open wound) exposure to blood, visibly bloody fluid, or other potentially infectious material.

If HIV serostatus of the source is unknown, voluntary HIV testing of the source should be sought. If rapid blood testing is available on site, it should be used to determine the HIV status of the source patient as results are usually available within 30 minutes. Rules regarding confidentiality and consent for rapid testing are identical to those for other HIV tests. In New York State, specific informed consent for HIV testing is required.

If the preliminary rapid test result is positive, the result should be given to the source patient. To establish a diagnosis of HIV infection, the test must be confirmed by a Western blot assay, which should be performed as soon as possible. If the result from testing the source patient is not immediately available and PEP is indicated based on assessment, the initiation of PEP should not be delayed pending the test result.

PEP should be initiated as soon as possible, ideally within 2 hours and generally no later than 36 hours post-exposure. The prescribing provider should ensure that the exposed worker has access to the full course of prophylactic antiretroviral medications.

Medications for PEP should be readily available to all workers. Employers should have a plan in place which specifies the following:

A procedure for providing PEP within 1 to 2 hours of an exposure. Location of a 24- to 48-hour supply of PEP for urgent use. A designated person with the authority for releasing drugs for PEP. A means by which a worker will obtain PEP drugs to complete the 4-week regimen

(some individuals may be reluctant to go to their local pharmacy) A mechanism for confidential baseline HIV antibody testing of the worker at the time the

occupational exposure is reported or within 72 hours of initiating PEP, and confidential HIV testing of the source as soon as possible after the exposure.

If the source patient's HIV test result is negative, the health care worker should be informed of the small chance that it could be a false-negative result if the source patient has been recently infected. PEP should be recommended in situations when a significant risk exposure has occurred and the clinician suspects that the source patient has a strong likelihood of having recently acquired HIV infection.

If a recommendation to begin PEP is declined, this decision should be documented in the medical record of the exposed worker.

All persons placed on PEP should be re-evaluated within 72 hours of their exposure. This allows for further clarification of the nature of the exposure, review of available source patient serologies, and evaluation of adherence to and toxicities associated with the PEP regimen.

A total of 4 weeks of treatment is recommended. This treatment duration is based on animal data and is generally recommended by HIV Specialists.

As of January, 2008, the following PEP is recommended in New York State:

Zidovudine 300 mg PO bid + Lamivudine 150 mg PO bid (or Combivir 1 PO bid) Plus Tenofovir 300 mg PO qd

OR

Zidovudine 300 mg PO bid Plus Emtricitabine 200 mg PO qd + Tenofovir 300 mg PO qd (or Truvada 1 PO qd)

An HIV Specialist or an occupational health clinician experienced in providing PEP should be consulted if there is any question about managing an exposure. Resources available for telephone or in-person consultation can be found on the New York State Department of Health AIDS Institute web site at www.hivguidelines.org.  In addition, the National AIDS/HIV Clinicians’ Consultation Center is available for PEP guidance at 1-888-448-4911.

 

What follow-up is recommended after a documented exposure to HIV infection?

Sequential confidential HIV testing should be obtained at baseline, 1, 3, and 6 months post-exposure even if PEP is declined. In New York State, if the test result is positive, a Western blot assay must be performed to confirm the diagnosis of HIV infection.

Because of the complexity and potential adverse effects of the treatment regimens, longitudinal care of the exposed worker should be provided either directly by, or in consultation with, an HIV Specialist or an experienced occupational health clinician who is familiar with the most current PEP guidelines, adverse effects associated with the treatment, and the emotional impact of an exposure.

HIV testing should be performed immediately if the exposed person develops an illness compatible with an acute retroviral syndrome.

Counseling and education should be provided. The exposed health care worker should be advised to abstain from sex or use condoms to avoid pregnancy and prevent sexual transmission of HIV. Newly infected persons generally test positive for HIV antibodies during the first 6 - 12 weeks after exposure. The exposed health care worker should avoid donating blood, plasma, organs, tissue or semen.