Direct detection of mycobacterial species in pulmonary specimens by two rapid amplification tests, the gen-probe amplified mycobacterium tuberculosis direct test and the genotype mycobacteria direct test.

Nucleic acid amplification tests have improved tuberculosis diagnostics considerably. This study evaluates a new amplification test, the GenoType Mycobacteria Direct (GTMD) test, for detection of the Mycobacterium tuberculosis complex, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium kansasii, and Mycobacterium malmoense directly in 61 sputum samples. Thirty (49.2%) samples were auramine smear positive, and 31 (50.8%) were smear negative. The GTMD results were compared to the Gen-Probe Amplified M. tuberculosis Direct (MTD) test results, using culturing and sequencing of the 16S rRNA gene as reference methods. The GTMD test could identify 28 of 29 samples containing the M. tuberculosis complex and was negative in a sputum sample containing M. intracellulare. The overall sensitivity and specificity results were 93.3% and 90.0% for the GTMD test, respectively, and 93.1% and 93.5% for the MTD test, respectively. The GTMD test is rapid and can be easily included in routine clinical laboratories for the direct detection of the M. tuberculosis complex in smear-positive sputum samples as an adjunct to microscopy and culture. Further studies are needed to evaluate the performance of the GTMD test for the detection of atypical mycobacteria.