Clinical Evaluation of BD MAX MDR-TB Assay for Direct Detection of Mycobacterium tuberculosis Complex and Resistance Markers.

BD MAX MDR-TB assay is a new molecular platform for the detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens and simultaneous detection of resistance toward isoniazid and rifampicin. This study assessed the assay's diagnostic accuracy by using pre-characterized MTBC culture-negative (n = 257), smear-negative/MTBC culture-positive (n = 93), and smear-positive/MTBC culture-positive (n = 153) respiratory specimens. Compared with culture, the overall sensitivity and specificity of BD MAX MDR-TB were 86.6% and 100%, respectively; sensitivities for smear-positive and smear-negative samples were 100% and 64.5%. Sensitivity and specificity for isoniazid and rifampicin resistance were 58.3% (biased low due to sample collection strategy in low prevalence setting), 99.3%, 100%, and 98.2%, compared with phenotypic drug resistance testing and 100%, 99.4%, 100%, and 99.4%, compared with GenoType MTBDRplus. In conclusion, BD MAX MDR-TB is an accurate assay for the diagnostic detection of MTBC in respiratory samples and its resistance toward the most important anti-TB drugs isoniazid and rifampicin. Due to its medium to high throughput, good validity, and ease of use, the assay will be of great benefit for medium-sized to large TB diagnostic centers.