Diagnosis
2.4.3 High complexity reverse hybridization NAAT
The "first in class" product for this class is the GenoScholar PZA-TB (Nipro, Osaka, Japan) for the detection of resistance to PZA. The GenoScholar PZA-TB test is based on the same principle as the FL-LPA and SL-LPA but requires the use of a large number of hybridization probes to cover the full pncA gene (>700 base pairs [bp]). Reading the hybridization results on the crowded strips with a total of 48 probes requires careful attention to avoid errors. However, it provides faster results than phenotypic DST and is based on molecular detection.
2.2.6 Urine LF-LAM assay
The urine LF-LAM assay is an immunocapture assay based on the detection of the mycobacterial LAM antigen in urine, and is a potential point-of-care test for certain populations being evaluated for TB. Although the assay lacks sensitivity, it can be used as a fast, bedside, rule-in test for HIV-positive individuals, especially in urgent cases where a rapid TB diagnosis is critical for the patient’s survival. The Alere Determine TB LAM Ag is currently the only commercially available urine LAM test endorsed by WHO.
2.2.5 LPAs
LPAs are a family of DNA strip-based tests that detect mutations associated with drug resistance:
- directly, through binding DNA amplification products (amplicons) to probes targeting the most commonly occurring mutations (MUT probes); or
- indirectly, inferred by the lack of binding the amplicons to the corresponding wildtype probes.
First-line LPAs (FL-LPAs) such as GenoType MTBDRplus and NTM+MDRTB Detection Kit allow the detection of resistance to RIF, INH and ETO. WHO recommends using FL-LPAs in the following situations (9):
Executive summary
The political declaration at the first United Nations (UN) high-level meeting on tuberculosis (TB) held on 26 September 2018 included commitments by Member States to four new global targets ³ , which were subsequently renewed at the second UN high-level meeting on TB on 22 September 2023⁴ . One of these targets is that at least 90 per cent of the estimated number of people who develop TB are reached with quality-assured diagnosis and treatment in the 5-year period 2023–2027³ .
