Transcript ALAT Chapter 10 - AZ Branch AALAS Homepage

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
object
Disinfection = reduction of number of pathogenic
microorganisms on an object to a harmless level
Sanitization = reduction of number of
microorganisms on an object to
acceptable public health standard
Sanitization = 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
microorganisms
Available 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 crosscontamination 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 mammal
Personnel 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) 938395. 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.