Prevention

• All procedures must be performed in such a way as to minimize or prevent the formation of aerosols and droplets (see Box 2).
• Mouth pipetting must be strictly prohibited.
• No materials should be placed in the mouth.

In general TB laboratories that perform diagnostic tests, an autoclave that uses saturated steam under pressure is the most efficient means of sterilizing instruments, glassware and media solutions; it is also used for decontaminating biological material (such as mycobacterial cultures). Two factors are essential for an autoclave to function optimally: (1) all of the air in the chamber should be replaced by steam; and (2) the temperature must be 121 °C.

In a laboratory where there is a moderate risk of infection, there are two levels of containment: the BSC (primary containment) and the laboratory itself (secondary containment). To address the specific risks associated with a moderate-risk laboratory, the following mitigation and control measures should be established.

TB laboratory facilities can be classified into three main levels of procedural risk, based on the activities being performed and their associated risks:

Risk is the combination of the likelihood that a specific hazard will be encountered and the consequences of an event related to that specific hazard. Risks should be identified and categorized, and a determination should be made about which risks need to be controlled or minimized. The analysis of aerosolization risks described in this manual has led to the development of minimum biosafety requirements necessary for performing different procedures in TB laboratories.

Personal protective equipment and clothing may act as barriers to minimize the risk of exposure to aerosols, splashes and accidental inoculation. The choice of clothing and equipment depends on the nature of the work. Protective clothing should be worn whenever staff work in the laboratory (see Box 6). Before leaving the laboratory, staff should remove their protective clothing, and wash their hands. Table 5 summarizes the types of personal protective equipment used in laboratories and the protection each type offers.

WHO consolidated guidelines on tuberculosis: tuberculosis preventive treatment, second edition

A2.1 Scope and objectives

The WHO consolidated guidelines on tuberculosis: tuberculosis preventive treatment make recommendations for the four milestones of the cascade of preventive care, namely, identification of risk groups, TB screening and ruling out TB, testing for TBI and choice and administration of the TPT regimen. The second edition of the TPT guidelines covers the same milestones.