Remarks

• This recommendation applies to all people living with HIV.
• The recommendation was extrapolated to children based on the generalization of data fromadults and limited data from children. For children, respiratory samples include sputum, BAL,induced sputum, nasopharyngeal aspirate and gastric aspirate.
• The recommendation was extrapolated to people with extrapulmonary TB based on thegeneralization of data from adults with pulmonary TB.
• The products for which eligible data met the class-based performance criteria for LC-aNAATsfor this recommendation were Xpert MTB/RIF Ultra (Cepheid, Sunnyvale, United States ofAmerica [USA]) and Truenat MTB-RIF Dx (Molbio, Goa, India). Data on MTB-RIF Dx weremore limited than those for Xpert Ultra.

Implementation considerations

• Diagnostic products in the low-complexity classes of tests should be prequalified by WHO or approved by another regulator before clinical use.
• Diagnostic test manufacturers, laboratory and programme managers, and policy-makers should be educated on the WHO PQ process for TB IVDs (https://extranet.who.int/prequal/).
• Ensuring sufficient volume and specimen quality is important to obtain accurate results.
• Safe waste disposal of used test consumables needs to be planned in advance to minimize environmental risk.
• Trace positive results on respiratory samples may present false-positive results for TB disease (M. tb. non-viable but DNA detected) in those that are HIV negative or not at risk for HIV, and those with a prior history of TB and an end of treatment within the last 5 years.
• For tests that do not have integrated rifampicin-resistance detection as an all-in-one test, reflex testing for resistance should be performed at the same time for all TB-positive patients to support universal access to DST for rifampicin, at a minimum, and to reduce the risk of loss to follow-up.
• In settings with a very low prevalence of rifampicin resistance7 , i.e. less than 2%, a positive test result for rifampicin resistance may represent a false positive result, and indicate a need for further testing with an alternative method or, at a minimum, repeat testing.
• If rifampicin resistance is detected, further resistance testing for fluoroquinolones and bedaquiline is essential to guide selection of a shorter multidrug-resistant TB or rifampicinresistant TB (MDR/RR-TB) treatment regimen.
• Use of a higher volume of CSF (≥6 mL) with concentration, where possible, is encouraged to increase the sensitivity of LC-aNAATs.