Operational Handbooks

WHO has long recommended use of TPT for populations at risk of TB, particularly those with HIV and child household contacts of TB patients.

The fourth step in the cascade of care for PMTPT is the choice of TPT regimen and providing support to people on TPT in completing their treatment.

TPT falls broadly into three categories: (i) isoniazid monotherapy for 6 or 9 months (6H or 9H), (ii) rifamycin-based shorter treatment and (iii) Lfx for 6 months (6Lfx) for people exposed to MDR/ RR-TB. Isoniazid preventive treatment (IPT) for 6 months was the mainstay of TPT until recently, for both adults and children, HIV-positive and HIV-negative, and in high and low TB incidence countries. Several systematic reviews have consistently demonstrated the efficacy of IPT in preventing TB disease among people infected with M. tuberculosis.

The epidemiology of TB in each setting and the social and the health-system contexts will inform decisions on a TB screening strategy, including how risk groups are prioritized, which screening approach to choose and whether screening of specific risk groups is feasible. Therefore, before embarking on detailed planning, a baseline assessment of the following features should be undertaken:

Class I BSCs work by drawing unfiltered room air in through a front opening, passing it over the work surface, and then expelling it through an exhaust duct.

Class I BSCs protect workers but do not protect work products (such as specimens or cultures) against contamination because unsterilized room air is drawn over the work surface.

The two types of BSCs described below are best suited for use in moderate-risk laboratories and in high-risk laboratories (TB-containment laboratories).

Class I

• This type of BSC provides personal and environmental protection but does not offer product protection. This lack of product protection may contribute to increased contamination rates, especially when preparing and inoculating liquid cultures (see Figure 1).

Class II

To address specific potential risks, the following biosafety requirements¹⁴ ¹⁵ should be established in a low-risk TB laboratory.

1. Use of bench spaces: The bench used to process specimens for direct sputum-smear microscopy or the Xpert MTB/RIF assay should be separate from areas used to receive specimens and from administrative areas used for paperwork and telephones.

Overall, serious adverse events leading to death or requiring withdrawal of TPT occur rarely. It is nevertheless critical to identify any sign of drug toxicity as soon as possible and to manage it immediately, particularly because people on TPT are usually healthy. Unmanaged drug toxicity may not only harm individuals but can also damage the reputation of a programme and result in widescale suspension of TPT due to loss of public confidence. As in any preventive action, health-care providers must weigh the risks and benefits of TPT for each individual.