MICROBIOLOGY
SAFETY ON THE CLINICAL
MICROBIOLOGY LABORATORY
NAME OF LECTURER
DATE OF LECTURE
OUTLINE
Laboratory Safety
A. Possible Routes for
Infection
Exposure Control Plan
Universal and Standard
Precautions
VIII.
A. Safety Guidelines for
the Laboratory
Personal Protective
Equipment
Engineering Controls
A. Biosafety Levels
IX.
B. Biosafety Cabinets
Postexposure Plan
Disposal of Hazardous
Waste
A. Autoclave
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V.
VI.
VII.
I.
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B. Sterilization
C. Disinfection
D. Antiseptics
E. Biocides
F. Liquid Decontaminants
Fire Safety
A. Type A
B. Type B
C. Type C
D. Type D
E. Class K
Chemical Safety
A. Material Safety Data
Sheet
B. Hazardous Chemicals
LABORATORY SAFETY
A. POSSIBLE ROUTES FOR INFECTION
Airborne
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Aerosols from centrifugation of unstopped tubes or from
heating cultures or specimens too rapidly, removing
stoppers from tubes, leakage from a container that holds
contaminated specimens
Ingestion
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Infection as a result of failure to wash hands or eating,
drinking, smoking, applying cosmetics, or pipetting w the
mouth
Direct inoculation
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Infection from needlesticks, broken glass, animal bites,
small scratches on the dingers
Mucous membrane contact
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Infection if the organism can directly enter through the
mucous membranes (conjunctiva of the eye)
Arthropod vectors
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Infectious sources include ticks, fleas, and mosquitoes
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II.
EXPOSURE CONTROL PLAN
Exposure control plan
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The risk of exposure to infectious agents for all job
classifications and explains exposure-reduction methods must
include:
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Safety education
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Universal precautions and safety standard precautions
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Engineering controls
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PPE
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Disposal of hazardous waste
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Postexposure procedures
III.
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UNIVERSAL AND STANDARD PRECAUTIONS
Centers for Disease Control (CDC)
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Universal precautions as recommendations that
describe handling of clinical specimens by health
care personnel; 1987
Clinical Laboratory and Standards Institute (CLSI)
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Universal precautions as set of preventive measures
designed to reduce the risk of transferring HIV, hepa
B virus, and other bloodborne pathogens in the
health care setting
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Apply to human blood and other body fluids w visible
blood but does not apply to feces, nasal secretions,
saliva (unless they contain visible blood)
Standard precautions
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Set of preventive measures applied to all patients
that are designed to reduce the risk of infection in
the health care setting
Potentially infectious
o
Blood, tissue, body fluids, secretions, excretions
(except sweat)
A. SAFETY GUIDELINES FOR THE LABORATORY
No food or drink
No smoking
No cosmetics
Protective eyewear must be worn
Wear face shields
Clothing: gowns, aprons lab coats, closed shoes
Hair should be tied up
Wash hands frequently and thoroughly
Eyewash stations: 100 feet or 10 secs away from any area in
the lab
10. Emergency stations: shower
11. Respirators: available where there is air contamination
12. Mouth pipetting: ingestion of microorganisms; use pipette
bulbs/automated devices
13. Glassware and sharps: in puncture-resistant containers
14. Centrifuges: minimize the production of aerosols
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IV.
PERSONAL PROTECTIVE EQUIPMENT
Protective laboratory clothing disposable gloves, eye
protection, face masks
Barrier protection: to prevent skin and mucous membrane
contamination
Gloves: worn when there is potential for skin contact w
potentially infectious materials; worn in phlebotomy and
capillary puncture
Facial protection and body covering: worn when splashes
w blood and other body fluids
High-efficiency particulate air respirators: should be fit
tested for each person; those who encounter mycobacteria
through contact w either patient or specimen
Lab employees who come in contact w body fluids should be
offered hepa B vaccinations for free
V.
ENGINEERING CONTROLS
To protect employees from the hazards that may occur during
the performance of lab procedures
All labs must adhere to a minimum of Biosafety Level 2
guidelines
A. BIOSAFETY LEVELS FOR INFECTIOUS AGENTS
Table 1. Biosafety Levels
BSL Function
1
No known pathogenic potential for immunocompetent
individuals
Bacillus subtilis
Most undergraduate lab courses operate at this level
Adherence to std lab techniques
2
Level 1 + lab coats, protective gloves, limited access,
decontamination of all infectious waste, biohazard signs
Apparatus includes partial containment equipment
1
Lab acquired infections: HBV, HIV, Staphylococcus, enteric
pathogens such as Salmonella and Shigella
Level 2 + special lab clothing, controlled access
Mycobacterium tuberculosis, Brucella, Coccidiodes
immitis, Rickettsia, arbovirus
Air movement must be carefully contained
Level 3 + entrance through a separate room, street clothing
→ lab clothing
Maximum containment
Filovirus, arenavirus
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4
Biohazard label
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Used to identify those areas of the lab where infectious
specimens or cultures are stored/present
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Figure 1. Biohazard label
Sterilization
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Done by heat, UV light, passage of air through HEPA filter
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BIOSAFETY LEVEL 2 CRITERIA FOR MICROBIOLOGY
PRACTICES
Limit access to lab when working w infectious agents
Decontaminate work surfaces at least once a day and after
any spill
Use mechanical pipetting devices
Do not eat, drink smoke, or use cosmetics. Do not store food
in biological refrigerator.
Wash hands thoroughly
Minimize the creation of aerosols
Wear lab coats, gowns, smocks and remove before leaving
the lab
Avoid skin contamination by covering cuts w occlusive
bandages and using gloves
Do not use needles that are bent, cut, or recapped
Handle M. tuberculosis at BSL 3 in Class II BSC while
wearing a solid-front gown and personal respirator (or facefolding mask); use sealed safety cups for centrifugation
Handle mild-lime fungi in BSC; plated media for myco should
be sealed w a cellulose band or cellophane or labelling tape
(prevent dispersion of spores)
B.
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BIOSAFETY CABINETS
i.
CLASS I BSC
Provide partial containment for procedures involving
moderate- and high-risk microorganisms (BSL 2 and 3)
Open-fronted, negative-pressure, ventilated cabinets
Unsterilized air enters and circulates w/in the cabinet
Exhaust air from cabinet is filter by HEPA filter
ii.
CLASS II BSC
Provide partial containment for procedures involving
moderate- and high-risk microorganisms (BSL 2 and 3)
Sterilize bot air entering and circulating w/in the cabinet and
the exhaust air
Vertical laminar-flow biological cabinets
Open-fronted; have HEPA filter, recirculated airflow w/in the
workspace
Exhaust air is filtered, too, by the HEPA filter
Type II-A
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Self-contained w 70% of the air recirculated
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Not required to be vented; acceptable for low- to
moderate-risk agents
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Most hospital microbio labs use this type
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Type II-B
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Must be vented w 30% of the air exhausted from the
cabinet and 70% recirculated back into the room
iii.
CLASS III BSC
Provide the highest level of safety
All air entering and leaving the cabinet is sterilized w a HEPA
filter
Supply air: drawn through the HEPA filter
Exhaust air: filtered through 2 HEPA filters
System is entirely enclosed
Infectious materials: handled w rubber gloves
VI.
POST EXPOSURE PLAN
All lab accidents or safety incidents: reported to the lab safety
officer or supervisor
Immediate and appropriate medical treatment
Administration of immunizations, hepa B immune
immunoglobulin, hepa B vaccinations
Collection of serum samples at 6 weeks, 3 mos, and 6 mos
for antibodies to HIV or abraded skin exposure to HBV or HIV
Documentation of the accident w a report
Corrective actions
VII.
DISPOSAL OF HAZARDOUS WASTE
Microbiological waste must be decontaminated before
disposal
Needles and sharps should be placed in puncture-resistant
containers
Contaminated materials should be placed into two leak-proof
plastic bags
Contaminated pipettes, swabs, and glass should be placed
into puncture-resistant burn boxes
A. AUTOCLAVE
Decontaminates that uses saturated steam at 121 oC and 15
psi of pressure for 1 hr to sterilize
Infectious medical waste: 132oC for 1/2 -1 hr
Monitored periodically
Bacillus stearothermophilus: spore indicator; weekly
monitoring
B. STERILIZATION
Physical or chemical process that kills all microorganisms,
including spores
Moist heat or steam under pressure: autoclave
Dry heat: 171oC for 1 hr, 160oC for 2 hrs, 121oC for 6 hrs
Liquid: glutaraldehyde, 6-30% hydrogen peroxide, 6-8%
formaldehyde, chlorine dioxide
C. DISINFECTION
Destroys most microbes but does not kill spores
Moist heat: 75-100oC
Liquid: glutaraldehyde, 3-6% hydrogen peroxide, 1-8%
formaldehyde, chlorine compounds, 70% isopropyl alcohol
Liquid household bleach
Quaternary ammonium compounds: benzalkonium chloride
D. ANTISEPTICS
For skin or tissue; not to be substituted for a disinfectant
Alcohols: 70% ethyl or isopropyl alcohol; not against spores
Iodophors: iodine combined w an organic carrier molecule;
povidone-iodine and poloxamer-iodine
Hexachlorophene: bactericidal and broad spectrum but may
be toxic
E. BIOCIDES
Chemical agents that inactivate microorganisms; either -static
and inhibit growth of the microbe or -cidal and kill the target
organism
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F. LIQUID DECONTAMINANTS
70% EtOH or 10% bleach (NaClO)
For 10 mins to increase ability to decontaminate
VIII.
FIRE SAFETY
Ignition sources: open flames; heating elements; spark
gaps, from light switches or static electricity; electrical
instrumentation
A. TYPE A
Water Fire Extinguisher
Used on combustible materials for fires in paper, wood,
rubber, sloth, plastics
Extinguish fire w cooling effect
X.
Question 1
Question 2
Question 3
REVIEW QUESTIONS
Answer 1
Answer 2
Answer 3
XI.
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REFERENCES
APA Format
B. TYPE B
Carbon dioxide fire extinguisher
Used on extremely flammable liquids or electrical fires
including fires of oil, kerosene, gasoline, paints, fats, grease,
solvents
Extinguish fire by eliminating oxygen
C. TYPE C
Dry chemical extinguishers
Used in electrical fires in wiring and other electrical sources or
equipment
Extinguish fire bc chemicals do not conduct electricity
D. TYPE D
Combustible metals
Used for fires involving combustible metals: Na, K, Mg, Na-K
alloys
NaCl salt wc forms a metal layer over the fire wc occludes the
oxygen
Graphite, sodium carbonate based, copper based
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E. CLASS K
Dry and wet chemical extinguishers
Used for kitchen fires involving combustible materials such as
oil or fat
Extinguish fire by using various wet or dry chemical agents
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IX.
CHEMICAL SAFETY
Every compound or reagent must have precautionary labels
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A. MATERIAL SAFETY DATA SHEET
Characteristics of hazardous compound chemicals
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Table 2. Sections of MSDS
Section
Information
I
Manufacturer’s name and address, emergency tel. no.,
tel no. for info about preparation
II
Hazardous ingredient’s identity info, components,
specific chemical identity common name, PEL
III
Physical/chemical characteristics
IV
Fire and explosion hazard data
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Reactivity data
VI
Health hazard data: routes of entry
VII
Precautions of safe handling and use
VIII
Control measures
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B. HAZARDOUS CHEMICALS
Corrosive: causes visible destruction or irreversible damage
to human skin on contact
Toxic: serious biological effects after inhalation, ingestion, or
skin contact w relatively small amts
Carcinogenic: ability of chemical to induce a malignant tumor
Ignitable: any chemical that can burn and includes both
combustible and flammable liquids
Explosive: reactive and unstable substances that readily
undergo violent chemical change
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