This document discusses laboratory safety procedures for working with tuberculosis (TB) specimens. It outlines the risks of TB in laboratory settings and recommends biosafety levels for different procedures. Direct smear microscopy carries a low risk while manipulating cultures poses a high risk. Biosafety level 3 practices and containment equipment are required for propagating cultures. Generating infectious aerosols is the main risk, so procedures that may aerosolize particles like processing specimens or cultures require biosafety cabinets and proper ventilation. Special precautions are also needed for multi-drug resistant (MDR) and extensively drug resistant (XDR) TB strains given the increased risks they present.

1. LABORATORY SAFETY
WORKING WITH
TUBERCULOSIS
Dr.T.V.Rao MD
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2. LABORATORY SAFETY – AS
DEFINED BY WHO
• Laboratory biosafety is the
process of applying a
combination of administrative
controls, containment principles,
practices and procedures, safety
equipment, emergency
preparedness, and facilities to
enable laboratory staff to work
safely with potentially infectious
microorganisms;
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3. Section 5 (a)(1) of the OSH Act states
Protects Health care Workers
• Section 5 (a)(1) of the OSH
Act states:
• “Each employer shall furnish
to each of his employees
employment and a place of
employment which are free
from recognized hazards that
are causing or are likely to
cause death or serious
physical harm to his
employees.”
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4. Where Is TB Found in the Workplace?
•Healthcare Facilities
•Correctional Institutions
•Homeless Shelters
•Long-term Care
Facilities for the Elderly
•Drug Treatment Centers
•DIAGNOSTIC
LABORATORIES
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5. Feasible and Useful
TB Abatement Methods
• Protocol for the early
identification of individuals
with active tuberculosis
• Medical surveillance
• Case management of
infected employees
• Worker training and
education
• Engineering controls
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6. Biosafety Levels
• Laboratory workers who
handle infectious materials
in the microbiology
laboratory should be
aware of the work
practices, safety
equipment, and barriers
that will protect them, and
others in the area, from
infectious agents
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7. BIOSAFETY AIMS AT
•Biosafety also
aims at preventing
unintentional
exposure to
pathogens or their
accidental release
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8. RISK OF TUBERCULOSIS TO
TECHNICIANS
• Infections with M.
tuberculosis are a
proven risk to
laboratory personnel as
well as others who may
be exposed to infectious
aerosols generated by
certain procedures.
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9. Increased risk of infection to laboratory staff
• Risk of infection with M.
tuberculosis is 3x to 9x higher for
TB lab workers than for other lab
workers
• Infection often results from
unrecognized production of
infectious aerosols containing
tubercle bacilli
• Infection can occur from needle
sticks, through broken skin, etc
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10. Laboratory personal should formulate biosafety to
meet the local needs in the Laboratory
• The biosafety level assigned
to the specific work being
done is driven by
professional judgement
based on an assessment of
the risk rather than by
automatic assignment of a
laboratory biosafety level
according to the particular
risk group assigned to a
pathogenic agent
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11. TYPES OF RISK IN THE LABORATORY WORKING
with TUBERCULOSIS
SPECIMENS
•1. Direct microscopy
– minimal risk
2. Processing
specimens –
moderate risk
3. Manipulating
cultures – high risk
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12. Key Recommendations working with
Tuberculosis specimens
•Key Recommendations: include 4 main protocols
1Work can be done on an open bench
2Access to the laboratory needs to be restricted
3 Separate bench for smear-preparation
required Adequately ventilated laboratory
with 6-12 air changes per hour (ACH) with
unidirectional airflow with either natural or
mechanical ventilation . 4 Proper
disposal of infectious material
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14. Biosafety Level Criteria and Requirements for
Handling Specimens Suspected of Containing
Mycobacterium tuberculosis
•All specimens suspected
of containing M.
tuberculosis (including
specimens processed
for other
microorganisms) should
be handled in a
biological safety cabinet
(BSC).
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15. USE OF PERSONAL EQUIPMENT
•Appropriate personal
protective equipment
(PPE) must be used.
At a minimum, this
includes gloves and
fluid-resistant
laboratory coat or
gown.
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16. Biosafety Levels (BSL)
• Conditions under which an
infectious agent can ordinarily be
safely handled. Conditions are a
combination of:
laboratory practices and
techniques safety equipment
laboratory facilities
Recommended BSLs for many of
the infectious agents have been
developed
• But different methods for the
same agent may require
different BSLs
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17. Risk Assessments for TB Procedures
•Based on likelihood of producing infectious
aerosols and the concentration of bacilli
•Limited risk for infectious aerosols direct AFB
smear microscopy Moderate risk for infectious
aerosols processing sputum specimens
High risk for infectious aerosols processing
cultures and suspension
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18. Using biological safety cabinets
• Laboratory-acquired
infections often result from
the unrecognized production
of infectious aerosols
containing tubercle bacilli. For
laboratories conducting TB
testing, the most important
hazard (or risk) is the
generation of infectious
aerosols since infection with
TB
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19. Making the smears for detection of
Mycobacterium
• Non-aerosol-producing
manipulations (eg, preparing
direct smears for acid-fast staining
when done in conjunction with
training and periodic checking of
competency) can be performed
using biosafety level-2 (BSL-2)
practices and procedures,
containment equipment, and
facilities.
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20. Safety level 3 practices in Tuberculosis
specimens
• SL-3 practices,
safety equipment, and facility
design and construction are
applicable to microbiology
laboratories that work with
indigenous or exotic agents
with a potential for
respiratory transmission, and
which may cause serious and
potentially lethal infection. If
the laboratory is propagating
and manipulating cultures for
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21. Safety level 3 practices in Tuberculosis
specimens
• BSL-3 practices, containment
equipment, and facilities are required.
Barriers include controlled access
to the laboratory and ventilation
requirements that minimize the
release of infectious aerosols
from the laboratory. Secondary
barriers should include self-closing
double-door access and negative
airflow into the laboratory. Exhausted
air must not be recirculated.
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22. AEROSALS ARE HIGHLY INFECTIVE
•Mycobacterium
tuberculosis occurs
primarily through
the inhalation of
infectious aerosols,
although it can also
occur through direct
inoculation or
ingestion.
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23. Generation of Aerosols with Tuberculosis
• Infectious aerosols may be
generated during the manipulation
of liquids containing tubercle
bacilli. After settling on surfaces,
droplet nuclei are not
reaerosolized and are considered
non-infectious
• Note .
• That is, M. tuberculosis bacteria are
usually transmitted only through
air, not by surface contact
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24. Direct AFB Smear Microscopy
•Limited risk of generating
infectious aerosols
•Work can be done on an
open bench restricted
access to the laboratory
separate bench for smear
preparation
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25. Direct AFB Smear
Microscopy•Adequately
ventilated
laboratory 6–12
ACH, directional air
flow natural or
mechanical
ventilation Proper
disposal of
infectious material
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26. Processing Sputum Specimens for Smear,
Culture, Molecular Tests – 1
•Moderate risk of generating infectious aerosols
during specimen manipulation Laboratories must
have restricted access and be separated from public
areas
•Impermeable surfaces for easy cleaning
•Air flows into lab without re-circulation to non-lab
areas (directional airflow)6–12 ACH, closed
windows
•Proper disposal of infectious material
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27. Processing Sputum Specimens for Smear,
Culture, Molecular Tests – 2
• Class I or II Biosafety Cabinets used for all open
manipulation of agents BSCs must be properly
installed and certified at least annually
• BSC exhaust may be ducted to outside using a hard
duct or thimble fitting (preferred) recirculated into
the room if assured that the BSC is functioning
properly
• Use aerosol-containment rotors
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28. TB and Respiratory Protection
• NIOSH certifies three
categories of non-powered
air purifying respirators
based on filtering efficiency.
All three categories are
acceptable for use against TB:
• Type 100 (99.97% efficient)
• Type 99 (99% efficient)
• Type 95 (95% efficient)
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29. TB Laboratory Biosafety Gaps
• What are minimum facility requirements?
• U.S./European-style BSL3? containment room, airflow, BSC?
• What are suitable laboratory layouts?
• What are minimum safety requirements for technicians who
are HIV+?
• for areas with high rates of MDR/XDR TB?
• When should respirators be required?
• Are Class I BSCs adequate?
• How to ensure functioning BSCs?
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30. CURRENT CONCERNS WITH
MDR TB and
XDR TB
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32. What is XDR TB
• XDR TB stems from poor general
TB control and the consequent
development of multidrug-
resistant TB (MDR TB). The current
definition of XDR TB is “XDR TB is
TB showing resistance to at least
rifampicin and isoniazid, which is
the definition of MDR TB, in
addition to any fluoroquinolone,
and to at least 1 of the 3 following
injectable drugs used in anti-TB
treatment: capreomycin,
kanamycin and amikacin.”
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33. emergence of XDR TB is
The emergence of XDR TB is a
recent phenomenon; evidence
indicating that XDR TB may be a
much higher risk organism from a
laboratory safety perspective may
yet emerge. In that event,
laboratory facilities must
reevaluate their own site-specific
risk assessments in order to
determine if additional safety
measures.
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34. Laboratory Safety Working with
XDR TB
• Like other strains of M. tuberculosis, XDR tubercle bacilli may
be present in sputum, gastric lavage fluids, cerebrospinal fluid,
urine, and in a variety of tissues.
2 Exposure to laboratory-generated aerosols is the most
important hazard encountered. Tubercle bacilli may survive in
heat-fixed smears and may be aerosolized in the preparation of
frozen sections and during manipulation of liquid cultures.
Because of the low infective dose of M. tuberculosis (i.e., ID50
<10 bacilli), sputa and other clinical specimens from suspected
or known cases of tuberculosis must be considered potentially
infectious and handled with appropriate precautions.
Accidental needle-sticks are also a recognized hazard.
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36. Laboratory activities with known XDR TB strains
• Research activities on XDR TB
strains, especially protocols
involving aerosolization of
infectious materials, should only
be undertaken if absolutely
necessary. Researchers and
institutions should review
protocols to determine if less
resistant strains of M.
tuberculosis can be used instead
of XDR TB strains.
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37. Using Disinfectants in tuberculosis
• Work surfaces must be
decontaminated, using the
laboratory-approved
disinfectant, upon completion
of procedures, immediately
following a spill, and at the
end of the work shift, if the
surface was re contaminated
since the last cleaning.
Laboratory equipment should
be routinely decontaminated.
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38. HAND WASHING A GREAT ACT TO PREVENT
SPREAD OF INFECTIONS INCLDUING TB
•Hands must be
washed upon
completion of work
with potentially
infectious materials
and before leaving
the laboratory.
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39. STOPPING TB A GREAT PRIORITY
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40. References
•Reference: CDC website. Available at:
•https://www.cdc.gov/tb/topic/laboratory/bi
osafetyguidance_xdrtb.htm. Accessed
November 29, 2017.
•Public health Resources on Tuberculois
•Google resources
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41. •Program Created by Dr.T.V.Rao MD for benefit
of laboratory manpower to prevent and control
spread of TB in Health care
•Email
•doctortvrao@gmail.com
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