Safety and specimen preparation black

Safety and Specimen Preparation

Types of Safety Hazards

BIOLOGICAL HAZARDS

The “ Chain of Infection”

Source (patient specimens with HCV, HIV, ..etc.)

↓

Method of transmission

↓

Susceptible host

Chain of infection and safety practices related to the biohazard symbol.

Hand washing

• Hand contact represents the number-one method of infection transmission.

• Hands should always be washed at the following times: – before patient contact – when gloves are removed– prior to leaving the work area– whenever the hands have been knowingly contaminated– before going to designated break areas– before and after using bathroom facilities.

Correct routine hand washing technique

1. Wet hands with warm water.2. Apply soap, preferably antimicrobial.3. Rub to form a lather, create friction, and loosen debris.4. Clean thoroughly between fingers, thumbs, and underfingernails and rings for at least 15 seconds and up to thewrist.5. Rinse hands in a downward position.6. Dry hands with a paper towel.7. Turn off faucets with a clean paper towel to preventrecontamination.

Personal Protective Equipment

- Gloves- Fluid-resistant laboratory coats- Goggles- Full-face plastic shield- Plexiglas countertop shields


Gloves: • are worn to protect the health-care worker’s hands from

contamination by: – Blood ─ Body fluid– Secretions ─ Excretions – Contaminated items

• and to protect the patient from possible microorganisms on the health-care worker’s hands.

• Wearing gloves is not a substitute for hand washing.• Hands must always be washed when gloves are removed.

A variety of gloves are available, including:

– sterile and nonsterile

– powdered and unpowdered

– latex and nonlatex

• Allergy to latex is increasing among health-care workers.

• Laboratorians should be alert for symptoms of reactions associated with latex contact.– irritant contact dermatitis (patches of dry, itchy

irritation on the hands) – delayed hypersensitivity reactions (24 to 48 hours

following exposure)– Immediate hypersensitivity reactions (facial

flushing and respiratory difficulty)

Latex Gloves Allergy

As many as 1 in 6 health professionals may be affected.

Latex Gloves Allergy • Natural rubber latex (NRL) gloves are made from

the milk-like fluid obtained from Hevea brasiliensis, the rubber tree

• NRL contains many proteins, including hevamine, hevein and (REF) rubber elongation factor

• Various chemicals are added during manufacture to provide strength, elasticity and stability

• Some NRL gloves add corn starch powder to prevent stickiness and aid donning

Latex Gloves Allergy • Constituents of a NRL glove can cause two types of

reactions . . .

• Allergic reactions (Type I and/or Type IV)an excessive immune response caused by external

agents such as NRL proteins and chemicals

• Irritant reactionsdo not involve the immune system they are caused by

localised physical damage by irritants such as glove powder

Latex Gloves Allergy - Prevalence

• Latex Allergy Amongst Healthcare Professionals

POPULATION PREVALENCE

Nurses 8 – 20%

Physicians (surgeons)

7.5 – 10%

Laboratory personnel

10%

BY ALLERGY TYPE

Latex Gloves Allergy - Mechanisms• Pathogenesis of Physical Urticaria

( hypersensitive vascular nervous system)

Latex Gloves Allergy - Mechanisms• Pathogenesis of Acute Immunological Urticaria

( IgE-dependent Type I Allergic Reaction)Sensitized individuals may develop cross-reactivity with fruits and vegetables which have molecular structures similar to latex e.g : Avocado, Banana,, Kiwi, Tomato, Potato

Approximately 60% of latex allergic individuals will go on to develop fruit allergies

Latex Gloves Allergy - Mechanisms• Pathogenesis of Acute Immunological Urticaria

( IgE-dependent Type I Allergic Reaction)

A range of symptoms can occur within minutes (immediate reaction):

- Contact urticaria - Rhinoconjunctivitis- Respiratory (asthma, bronchospasm)- Life-threatening anaphylaxis in extreme cases

Symptoms normally resolve rapidly when exposure ceases

Latex Gloves Allergy - Mechanisms• Pathogenesis of Allergic Contact Eczema “Dermatitis”

( non-toxic event, sensibilization causes Type IV Allergy)

Latex Gloves Allergy - Mechanisms• Pathogenesis of Allergic Contact Eczema “Dermatitis”

( non-toxic event, sensibilization causes Type IV Allergy)

In sufficient quantities ,macrophages can damage the skin resulting in a Type IV allergic contact dermatitis within around 6 to 48 hours (delayed reaction)

Type IV symptoms include :–Pain and itching–Blisters, sores and vesicles

When exposure ceases symptoms normally resolve within 3 to 4 weeks


Fluid-resistant laboratory coats

• Protect skin • Prevent soiling of clothing during:

– Procedures – Patient-care activities that are likely to generate splashes of :

• Blood• Body fluids• Secretions• Excretions


Goggles, Full-face plastic shield, Plexiglas countertop shieldsProtect mucous membranes of the eyes, nose, and mouth during:

– Procedures– Patient-care activities that are likely to generate splashes or sprays of:

• Blood• Body fluids • Secretions • Excretions

Occupational Health and Bloodborne Pathogens

• Take care to prevent injuries when using needles, scalpels, and other sharp instruments.

• Never recap used needles or otherwise manipulate them using both hands.

• Never use any technique that involves directing the point of a needle toward any part of the body.

• Use either a one-handed “scoop” technique or a mechanical device designed for holding the needle sheath.


• Place used disposable syringes and needles, scalpel blades, and other sharp items in appropriate puncture-resistant containers


• Proper needle disposal Improper needle disposal

22/2/2009 27Collected and Prepared by Dr. Walid Ahmad Nouh

Biological Waste Disposal

• All biological waste, except urine, must be placed in appropriate containers labeled with the biohazard symbol.

• This includes specimens and the materials with which the specimens come in contact.

• Any supplies contaminated with blood and body fluids must also be disposed of in containers clearly marked with the biohazard symbol or with red or yellow color-coding.

• This includes alcohol pads, gauze, bandages, disposable tourniquets, gloves, masks, gowns, and plastic tubes and pipettes.

Biological Waste Disposal

• Contaminated non-disposable equipment, blood spills, and blood and body fluid processing areas must be disinfected.

• The most commonly used disinfectant is a 1:10 dilution of sodium hypochlorite (household bleach) prepared weekly and stored in a plastic, not a glass, bottle.

• The bleach should be allowed to air-dry on the contaminated area prior to removal.

Occupational Exposure to BloodbornePathogens

• Any accidental exposure to blood through: – Needle stick– Mucous membranes– Non intact skin

• A confidential medical examination must be immediately started.• Evaluation of the incident must begin right away to ensure appropriate

postexposure prophylaxis (pep).

• Needle sticks are the most frequently encountered exposure and place the laboratorian in danger of contracting HIV, HBV, and hepatitis c virus (HCV).

CHEMICAL HAZARDS

General Precautions

• Avoid getting chemicals on your body, clothes, and work area.

• Wearing safety goggles when pouring chemicals

• Observing strict labeling practices; and following instructions carefully.

• Preparing reagents under a fume hood.

CHEMICAL HAZARDS

General Precautions

• Chemicals should never be mixed together, unless specific instructions are followed, and they must be added in the order specified.

• This is particularly important when combining acid and water, as acid should always be added to water to avoid the possibility of sudden splashing.

• When skin or eye contact occurs, the best first aid is to immediately flush the area with water for at least 15 minutes and then seek medical attention.

• Laboratorians must know the location of the emergency shower and eyewash station in the laboratory.

• Do not try to neutralize chemicals spilled on the skin.

Material Safety Data Sheets

• All chemicals and reagents containing hazardous ingredients in a concentration greater than 1 percent are required to have a material safety data sheet (MSDS) on file in the work area.

• An MSDS contains information on physical and chemical characteristics, fire, explosion reactivity, health hazards, primary routes of entry, exposure limits and carcinogenic potential, precautions for safe handling, spill cleanup, and emergency first aid.

• Containers of chemicals that pose a high risk must be labeled with a chemical hazard symbol representing the possible hazard, such as flammable, poisonous, corrosive, and so on.

Chemical Waste Disposal

Many kits used in testing contain sodium azide, which can be disposed of by flushing down the drain with plenty of water to avoid buildup in plumbing.

RADIOACTIVE HAZARDS

General Precautions

• Radioactivity is encountered in the clinical laboratory when procedures using radioisotopes, such as radioimmunoassay, are performed.

• The amount of radioactivity present in most medical situations is very small and represents little danger

RADIOACTIVE HAZARDS

• The effects of radiation are related to the length of exposure and are cumulative.

• Exposure to radiation is dependent on the combination of time, distance, and shielding.

• Persons working in a radioactive environment are required to wear measuring devices to determine the amount of radiation they are accumulating.

RADIOACTIVE HAZARDS

• Laboratorians should be familiar with the radioactive symbol.

• This symbol must be displayed on the doors of all areas where radioactive material is present.

• Exposure to radiation during pregnancy presents a danger to the fetus.

• Personnel who are or who think they may be pregnant should avoid areas with this symbol.

SEROLOGICAL TESTING

Specimen Preparation and Processing

• The most frequently encountered specimen in immunological testing is serum.

• Blood is collected aseptically by venipuncture into a clean, dry, sterile tube.

• Care must be taken to avoid hemolysis, since this may produce a false positive test.


• Serology : The study of a noncellular portion of the blood known

as serum.

• Serum :Fluid expressed from clotted blood or from clotted

blood plasma. Roughly, plasma deprived of fibrinogen and other clotting proteins.

• Plasma : Clear yellowish fluid of vertebrates, clotting as easily

as whole blood and obtained from it by separating out suspended cells by centrifugation.

An aqueous mixture of substances, including plasma proteins.

Serum Sickness

• Historically, after the administration of antitoxins containing foreign serum, such as horse antitetanus or antidiphtheria serum.

• In such cases, the recipient of a foreign antiserum develops antibodies specific for the foreign serum proteins; these antibodies then form circulating immune complexes with the foreign serum antigens.

• Typically, within days or weeks after exposure to foreign serum antigens, an individual begins to manifest a combination of symptoms:

- Fever -Weakness- Generalized vasculitis (rashes) (deposition in the arteries) - Edema - Erythema - Lymphadenopathy - Arthritis (deposition in the synovial joints) - Glomerulonephritis (complex deposition in the kidney)


• Hemolysis : damaging of the red blood cell membrane releasing hemoglobin, enzymes and electrolytes.

22/2/2009 47Collected and Prepared by Dr. Walid Ahmad Nouh


• The blood specimen is allowed to clot at room temperature or at 4°C and then centrifuged.

• Serum should be promptly separated into another tube without transferring any cellular elements.

• Fresh, non heat inactivated serum is usually recommended for testing.

• However, if testing cannot be performed immediately, serum may be stored between 2°C and 8°C for up to 72 hours.

• If there is any additional delay in testing, the serum should be frozen at –20°C or below.

Centrifugation

• It is the process of using centrifugal force to separate the lighter portions of a solution, mixture, or suspension from the heavier portions.

A centrifuge • is a device by which centrifugation

is effected.

Centrifugation

• In the clinical laboratory, centrifugation is used to :

1. Remove cellular elements from blood to provide cell-free plasma or serum for analysis.

2. Concentrate cellular elements and other components of biological fluids for microscopic examination or chemical analysis.

3. Remove chemically precipitated protein from an analytical specimen.

4. Separate protein-bound or antibody-bound ligand from free ligand in immunochemical and other assays.

5. Extracts solutes in biological fluids form aqueous to organic solvents.

6. Separate lipid components from other components of plasma or serum.

TYPES OF CENTRIFUGATION

Centrifugation

Lymphoprep™Isolation of human mononuclear cells

• A simple and effective method for the isolation of mononuclear cells from human blood was reported by Dr. Arne Bøyum in 1968.

• For more than 35 years a commercial medium known as Lymphoprep ™ has been widely used for isolating these cells.

Lymphoprep™Isolation of human mononuclear cells

• Mononuclear cells (monocytes and lymphocytes) have a lower buoyant density than the erythrocytes and the polymorphonuclear (PMN) leukocytes (granulocytes).

• The vast majority of mononuclear cells have densities below 1.077 g/ml.

• These cells can therefore be isolated by centrifugation on an isoosmotic medium with a density of 1.077 g/ml, which allows the erythrocytes and the PMNs to sediment through the medium while retaining the mononuclear cells at the sample/medium interface.

TYPES OF CENTRIFUGES

Types of centrifuge

CENTRIFUGE SPEED

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