Biosafety in TB Laboratory: Factors to be Considered in TB Laboratory Risk Assessment

Staff working with patient specimens and live mycobacterial cultures must operate under appropriate biosafety conditions with adequate infection control measures in place, including staff health checks.

For the safety of personnel working in TB labs, the following factors must be considered to avoid the risk associated with pathogenicity and transmission of TB bacilli.

The 4 key factors that must be considered during risk assessment of TB labs include:

1. The organism i.e., M. tuberculosis: Different strains of TB carry different levels of individual and community hazards. The following should be considered:

• Route of transmission (Inhalation of aerosols)
• TB epidemiology and patient population served by the laboratory (drug-sensitive TB, drug-resistant TB, non-TB patient proportions): MDR and XDR strains carry higher risks and cause greater harm to the infected individual as treatments may be limited or less effective.

2. Specimen Handling: Procedures involving generation of aerosols are more hazardous. The following should be considered:

• Bacterial load in the environment
• Viability of bacilli in sputum specimens and cultures
• Manipulations (centrifugation, vortexing, and vigorous shaking) that are likely to generate infectious aerosols  

3. Staff and Workload: Individuals in the laboratory differ in their susceptibility to TB, higher-risk individuals may be less experienced, over-worked or have an underlying health condition. The following should be considered:

Level of experience and competency of the laboratory staff:

• Training status of staff to perform laboratory procedures
• Staff’s competency procedures in handling potentially infectious material and response to emergencies
• Ability of the staff to use biosafety equipment properly
• Review of the technical proficiency of staff
• Staff proficiency in using aseptic techniques and Biological Safety Cabinets (BSCs)
• Staff willingness to accept responsibility for protecting themselves and co-workers

Health status of staff: Higher-risk groups include:

1. Individuals with reduced immunity which may be caused by certain medications
2. HIV-infection or pregnancy may increase the risk of becoming infected with TB
3. Diabetic individuals

4. Location of the Laboratory:  TB Laboratories are generally located away from the main health facilities in separate building with unrestricted entrance to the building. If the laboratory cannot be located in a separate, dedicated building, separation may be achieved by placing the laboratory at the blind end of a corridor. TB containment laboratories should have access only to authorized staff through an anteroom.

Resources

• Tuberculosis Laboratory Biosafety Manual, 2012, WHO

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