At the peripheral level (Level I), laboratories offer a range of basic diagnostic tests with the focus on providing initial testing to rapidly detect TB (and RIF resistance):
- The LF-LAM is an instrument-free, point-of-care test that delivers results within 15-20 minutes and is suitable for use in the clinic. Current recommendations are limited to use among People with HIV with preset criteria. Thus, antiretroviral therapy (ART) initiation sites or similar care centres for People with HIV would be examples of appropriate placement sites. The LF-LAM is a complementary test to be used with other tests, particularly because it lacks drug-resistance detection, and this should also be considered.
- Acid-fast bacilli (AFB) smear microscopy is widely used. Existing smear microscopy sites are suitable for placement of Xpert MTB/RIF and Ultra, as well as Truenat MTB and MTB Plus because the same population is served and the infrastructure requirements are similar. These mWRDs offer the advantage of higher sensitivity for TB detection and detection of RIF resistance. The Truenat MTB can run on battery for periods of time and is thus useful where the electricity supply is unstable; also, it can operate at higher temperatures (up to 40 ᵒC) (34).⁴⁰
- TB-LAMP is also suitable for placement at the peripheral level. It is less automated and somewhat more complex to perform than other tests (e.g. Xpert MTB/RIF or Truenat MTB) but is cheaper than other mWRDs and can replace microscopy for initial TB testing. However, because it does not detect RIF resistance, an alternative test should be considered in populations at high risk of MDR-TB, particularly where follow-on testing for RIF resistance is not accessible or available.
- The low complexity automated NAATs that detect FQ and INH resistance are also technologically suited to the peripheral level. However, these tests are used as follow-on tests to the primary tests for TB detection (and RIF resistance detection). An important factor to consider, especially since these tests require a different instrument to that presently used for Xpert assays, is that the number of tests needed over a certain period will be much lower than the number for initial TB diagnosis. Furthermore, since the test has important value in providing rapid results on FQ, ETO and AMK resistance for management of MDR/RR-TB, consideration should be given to placing these tests at sites where MDR/RR-TB treatment is delivered.