Chapter Ten

Hygiene in the Laboratory Animal Facility

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Sterilization, Disinfection & Sanitization

Difference between sterilization, disinfection & sanitization is a matter of degree of cleanliness.Sterilization = destruction of all organisms on an

objectDisinfection = reduction of number of pathogenic

microorganisms on an object to a harmless levelSanitization = reduction of number of

microorganisms on an object to

acceptable public health standardSanitization = make an object

aesthetically pleasing & clean

Sterilization

Autoclaves sterilize by exposure to moisture at high temperature & pressure.

Autoclaving is fast, reliable, relatively cheap.

Autoclaving avoids the use of toxic chemicals.

Autoclaving Microorganisms, type & size of material being

sterilized determines autoclaving time. large bags of bedding, nested shoebox cages or heavily

wrapped surgical instruments Items should be autoclaved for at least 15 min. at

250°F & with a pressure of 15 psi. High pressure allows steam to be superheated.

Some items cannot be autoclaved because of sensitivity to heat, moisture or high pressure.

Other sterilization techniques include:ethylene oxide gas, dry heat sterilization, chemical

sterilization, gamma irradiation & liquid filtration

Disinfection

Disinfectants too strong for use on living animals.

Classified according to type of microorganism they are most effective against.

End in “–cidal” has killing action.

End in “–static” inhibits microorganism growth.

Bacteriostat prevents growth, does not necessarily kill.

Bactericidal kills bacteria, not necessarily spores.

Sporicidal kills spores & bacteria.

Chemicals, such as phenols, bleach & quaternary ammonia disinfect objects.

Disinfection II Bleach is a superior disinfectant.

It kills many types of bacteria & viruses, is inexpensive & available. It does not contain dirt-loosening detergents.< effective if surface not cleaned of organic matter.

Phenolic compounds were popular disinfectants.High concentrations needed to produce disinfection.Cats react adversely to phenol.

Quaternary ammonia compounds are weak.Destroy cell membranes of certain types of

microorganismsAvailable as virucides, algicides or fungicides Less effective when mixed w/ detergents or soaps.

Combination neutralizes disinfecting capability.

Sanitization

Number of bacteria on inanimate objects reduced enough to prevent disease.

Routine cleaning of items such as floors, cages, walls, feeders, sinks, implements & tables

Removes dirt, hair, dust, saliva, blood, feces, urine.Wash w/ detergent & rinse w/ water at 180°F.

Deodorants not used in place of sanitization. Indiscriminate mixing of chemicals can cause reactions hazardous to animals & people.

Chemical Guidelines

Guidelines concerning handling of chemicals:Store chemicals in a cool, central area.Follow the instructions on label.Never use a container that is not labeled.Do not make an assumption as to contents.Never mix two chemicals together unless authorized by

manufacturer.Mixing ammonia & bleach produces a toxic gas.

Cage Changes

The Guide: Cages should be changed often enough “to provide a

healthy environment for animal, in accord with its normal behavior and physiologic characteristics.”

Generally change solid-bottom cages 1-2 x/wk. Generally drop-bottom cages changed 1x/2 wks. Number of animals in a cage, cage size & type of

bedding affect change cage frequency. Larger animals (dogs, cats, nonhuman primates)

- daily cleaning & bedding replacement. AWA reg’s set minimum cleaning standards for

cages, feeders & water bottles.

Equipment Cleaning Techniques

No hand cleaning in animal room.Airborne microorganisms contaminate environment.

Pass-through washers have clean & dirty side. Soiled equipment delivered to dirty side.

Cages scraped free of most bedding, feces & debris.Chemical descalers remove most of urine scale.

Feeders & dishes are scrubbed free of debris. Bottle brush loosens deposits inside bottles. Sipper tubes rinsed, washed in a cage washer. Equipment too large to fit into cage washers should

be vigorously hand-scrubbed or pressure washed, using detergents and disinfectants.

(Image) Washing Dog Run Flooring

Room Cleaning Schedules & Techniques

Sinks - clean, free of clutter & stocked. Vents and doors - kept free of dust, grime, hair...

clogged vents reduce air circulation. Trash cans - disposable plastic liners, emptied

frequently, & disinfected regularly. Animal rooms - emptied, cleaned & disinfected on

fixed schedule.Clean walls, ceilings, lights & all exposed surfaces.Clean sink, broom, mop & bucket after each use.Replace or launder mop heads frequently.Keep cleaning items in room where they are used.

Use ONLY for cleaning of that room.Reduces chance of spreading disease from room to room.

(Images) Room Cleaning

Other Equipment Changes

Racks w/ built-in cages - wash > 2 x/mo.

Cleaning feeders depend on number &

type of animals being fed & type of diet.

Critical to inspect water bottles, automatic valves & sipper tubes daily to be sure working.

Replace used water bottles w/ sanitized bottles.Put refilled bottles back on cages from which they came

to prevent cross-contamination.

Watering equipment should be thoroughly flushed before reconnecting rack to room water lines.

Racks should be stored w/ empty water lines.

Environmental Monitoring

Temp tapes used to evaluate efficiency of sanitization.

Temp indicator monitors for proper washing & rinsing temps.One type is a strip labeled w/ heat-sensitive indicator. Indicator is attached to surface of equipment, which is

then sent through washer.Strip indicates highest water temp on surface.Rinse water temperature should reach at least 180°F.

Environmental Monitoring II

Bacterial culture - testing for bacteria on surface of clean cages & equipment that have been through cage washer is also a common monitoring method.

Small plastic dishes containing a nutrient substance suitable for bacterial growth are pressed onto surface of a clean area.

Small plastic dish is placed in an incubator or allowed to sit at room temp 24 hrs.

Bacteria present on cage surface will grow on nutrient substance & indicate effectiveness of cleaning procedure.

Vermin Control

A properly constructed building, good housekeeping program & proper waste disposal help control vermin populations. flies, fleas, cockroaches, ticks, wild rodents...

Vermin enter on feed, bedding, and humans, and through cracks & small openings.

Keep areas sanitary, dispose of food & bedding, close doors & seal cracks.

Wild rodents that enter a

facility must be trapped. Use of pesticides in animal

areas should be strictly controlled.

Pesticides

Investigators must consent to their use, as pesticides, just like deodorants, can compromise experimental results.

These chemicals must not be allowed to contact the animals or their feed, bedding or water.

As part of a comprehensive control program, relatively harmless chemicals, such as boric acid and amorphous silica, can help control cockroach infestations.

Personal Safety & Hygiene Protective clothing:

prevents contact w/ infectious, toxic or corrosive agents type needed depends on procedures being performed

Non-slip bottoms & steel-toed shoes

offer protection against slipping as well

as from dropped equipment injuries. Disposable shoe covers prevent cross-

contamination in germ free,

quarantine & isolation areas. Only wear work shoes in facility. Ear protectors recommended in noisy areas in

which average noise level is >85 decibels.

Goggles & Uniforms

Goggles offer the best protection, because they cover the entire eye and surrounding area.

Facilities should also have eyewash stations in areas where chemical splashes could occur.

Closely fitted face masks are most effective in preventing personnel from inhaling contaminants.

Street clothes should not be worn while working in an animal facility, and uniforms should not be worn outside the facility.

Uniforms protect personnel &

environment outside facility

against contamination.

Gloves

Leather gloves of various lengths are worn to handle animals that bite or scratch.

Some reinforced w/ metal for bite protection. Heat-resistant to handle hot items or dry ice. People w/ contact skin allergies to animals should

wear disposable plastic or latex gloves. Special gloves are available for people who have

allergies to latex or powder.

Personal Hygiene Practices

Safety and personal hygiene guidelines: Store & consume food in designated areas of facility.

Keep hands away from mouth, nose, eyes, face & hair.

Smoke only in assigned areas.

Always wash hands: after removing dirty PPE

before applying makeup, smoking or eating

before leaving animal room or cage washing area

Do not wear jewelry that interferes w/ hand washing.

Some facilities require employees to shower before entering and/or exiting animal areas.

Occupational Health Program

A pre-employment physical exam, medical history & vaccinations are part of program,

Tetanus - spore-forming bacteria in environment.Personnel who handle animals or clean up after them are

exposed to these spores. Infection follows deep puncture wounds which are difficult

to clean by conventional washing.

Rabies - virus which can occur in any mammalPersonnel who handle animals obtained from animal

shelters should be inoculated w/ pre-exposure vaccine.

Hepatitis - virus that infects liver.Most cases acquired from from nonhuman primates.Personnel who work w/ primates are often vaccinated

Occupational Health Program II

Zoonotic agents are infectious

agents that can be transmitted

from animals humans.TB, measles & salmonellosis

Personnel who work with NHP

run a higher risk of exposure to TB.Handlers have tuberculosis tests performed regularly.

All injuries & accidents must be reported to supervisor, regardless of how insignificant.

Immediately wash bite wound w/ soap & water.Notify supervisor of bite as quickly as possible.Report location of bite and animal that bit them.

Occupational Health Training

In addition to providing protective equipment and vaccinations, a research facility is also required to provide training of personnel in the areas of proper use of equipment, zoonotic diseases, blood-borne pathogens and other areas which can be hazardous to employees.

Additional Reading

Biosafety in Microbiological and Biomedical Laboratories. HHS Publication No. (CDC) 93-8395. 3rd. Edition US Government Printing Office, Washington, D.C. 1993.

Occupational Health and Safety in the Care and Use of Research Animals. National Research Council. National Academy Press, Washington, D.C. 1997.