TB Laboratory Safety: Practices and PrinciplesAn International Perspective

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TB Laboratory Safety Practices and Principles-An
International Perspective
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Pathogenesis of Tuberculosis

• Globally, millions of people have tuberculosis
  (TB)
• Transmission by aerosols
• Agent - Mycobacterium tuberculosis (M.tb)
• Infection vs. disease
• Infection may be latent or progress to
  disease
• Primarily affects lungs but may infect other
  organs

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M.tuberculosis

• - acid-fast rod shaped bacterium
• - resist decolorization w acid alcohol
• - mycolic acid and waxes in cell wall
• - does not release stain primary stain

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Pathogensis

• - ability of organism to cause disease
• - route of transmission
• - stability of organism
• - infectious dose
• - concentration of organisms per volume
• - origin of agent
• - condition of host

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Direct Smear Microscopy

• -primary method for diagnosis of TB
• -perform without personal respiratory
• protection
• -No documented transmission on open
• bench
• -increased risks when HCWs have contact with
  coughing patients
• -administrative controls should limit this
• exposure

WHO. 1999. Guidelines for Prevention of
Tuberculosis in Healthcare facilities in
resourcelimited settings
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Laboratory Arrangement for AFB Smear Microscopy

• Plan the lay out of laboratory room for an ease
  and safe work area
• Plan areas for each step and the movement of the
  sputum and work with AFB smears
• Movement of people in the work area must be
  minimized

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• Laboratory Arrangement

staining
Microscopy
Recording/Reporting
Smear prep
Reception of sputum
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SAFE DISPOSAL OF WASTE MATERIALS

• Infectious waste can be divided in two types
• Disposable and re-usable materials
• Infectious TB lab waste is a risk to health care
  workers and the community
• Waste must be sterilized or disinfected before it
  leaves the laboratory
• Discard contaminated materials and sputum
  containers in 5 Phenol disinfectant

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Disposable of Materials

• Incinerate Use temperature not less than 100 0
  degrees and dump in a hole or autoclave (if
  autoclaves is available) 
• Dump hole Place waste in hole (about 1 m) and
  burn
• Cover hole with wood or a plate when half filled
  to prevent access by people, animals and birds

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Re-usable Materials

• Place slide holders, forceps in a container with
  disinfectant
• Boil 20 min or more-or autoclave and wash for
  re-use

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• FLOW CHAR FOR DISPOSAL OF SPUTUM CONTAINERS

CONTAMINATED CONTAINERS
DISPOSABLE
RE-USABLE
BUCKET 5 PHENOL
BUCKET 5 PHENOL
DEEP HOLE BURNING BURY
INCINERATION
STERILIZATION FOR REUSE
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• FLOW CHART FOR DISPOSAL OF INFECTIOUS WASTE FROM
  TB LABORATORY

Infectious waste
2.Reusable
1.Disposable
Autoclave
Disinfect
Disinfect
Autoclave
Incinerate
Wash
Dump

• Graduated pipettes

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IMPORTANT POINTS TO REMEMBER 

• Autoclaving is the safest and most satisfactory
  method of sterilization
• If autoclave is not available incinerate or burn
  the infectious waste
• Disinfect TB work surface areas with cotton
  wool soaked in 5 Phenol.

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Risk Assessment

• Provide information to keep people safe
• Shared responsibility of both managers
• and employees
• Best assessors - first line supervisors/
• technologists
• Effective planning is important

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Risk Assessment

• Background information and ability to visualize
  potential outcomes
• Review laboratory records
• -equipment maintenance
• -employee training
• -environmental monitoring
• -injury and surveillance reports
• Inspect the laboratory
• -periodic walk-throughs
• -formal inspections by certifying agencies

1998. Laboratory Risk Assessment What, Why and
How. Centers for Disease Control and Prevention
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Risk Assessment - Contd
When should assessment be done?

• Regular intervals, at least annually, more
  frequently if problems are discovered
• When a change occurs in the lab
• -relocation or renovation
• -new employee(s)
• -new infectious agent or new reagent
• -new test or equipment

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Biosafety Cabinets (BSC)

• BSC - Class I
• -draws air into the cabinet and exhausts
• -protects environment from aerosols
• -produces negative pressure in the room
• -type of cabinet needed in most laboratories
• BSC - Class II
• -laminar flow and exhausts air
• -protects specimen and HCW
• -poor practices/maintenance increase hazard
• Monitor air flow daily for both types of cabinets

WHO. 1999. Guidelines for Prevention of
Tuberculosis in Healthcare facilities in
resourcelimited settings
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Biosafety Cabinets (BSC)

• Provide protection when used with appropriate lab
  
• practices
• Improper use and poor maintenance can be
• hazardous to the HCW and others in the work area
• -Bunsen burners disrupt air flow patterns
• -Contaminated hands/gloves endanger all lab
  staff
• Require daily monitoring and annual certification

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Biological Safety Cabinet
SterilGARD III Advance, The Baker Company
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Safety with Suspensions of M.tb

• Cultures, drug susceptibility and other tests
• -use ventilation in work areas
• -reduce the of labs handling concentrated
• specimens
• -use biosafety cabinets to perform these
• procedures
• -well trained HCWs

WHO. 1999. Guidelines for Prevention of
Tuberculosis in Healthcare facilities in
resourcelimited settings
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Aerosol Producers
Vortex
Pipettes
VWR International
Raymond A. Lamb, LLC
Tubes
Beckman Coulter, Inc.
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Centrifuge
Aerosolve Cannister
Avanti J-E, Beckman Coulter, Inc.
Rotor
Beckman Coulter, Inc.
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Safe TB Laboratory Practices

• Perform risk assessment
• Control ventilation and airflow patterns
• Prevent leaking specimen containers and
  contaminated work forms
• Frequent and appropriate hand washing

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Safe Practices contd

• Prevent aerosols and spills
• Use of disinfectants and proper waste disposal
• No eating, drinking or smoking in the lab
• Have an emergency plan and supplies available

WHO. 1998. Laboratory Services in Tuberculosis
Control Organization and Management Part I
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References

• 2000. TB Microscopy in Pacific Island countries
  Japan International Cooperation Agency and The
  research Institute of Tuberculosis
• Date of Publication. Acid-fast Direct Smear
  Microscopy,WHO, IUATLD, CDC, KNCV, JATA, APHL
• Draft publication. External Quality Assessment
  for AFB Microscopy
• 1995. Mycobacterium tuberculosis assessing your
  laboratory. ASTPHL and CDC.
• 2002. Zambia AFB microscopy Training Manual.
  Central Board of Health.
• 1993, Channel BTE CO, Inc. About Tuberculosis,
  Booklet 37788. Southfield, MA.
• 1998. Laboratory Risk Assessment What, Why and
  How. Centers for Disease Control and Prevention
• WHO. 1999. Guidelines for Prevention of
  Tuberculosis in Healthcare facilities in
  resourcelimited settings