Use of the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test for Early Detection of Mycobacterium tuberculosis in BACTEC 12B Medium

To achieve better sensitivity than direct testing and better turnaround time than current culture and identification methods, the Gen-Probe Mycobacterium Tuberculosis Direct method was used to detect Mycobacterium tuberculosis in BACTEC 12B medium cultures when they first gave a growth index (GI) of at least 10 (MTD/BACTEC method). Of 179 acid-fast, smear-positive specimens that were culture positive for M. tuberculosis, all were positive by the MTD/BACTEC method (sensitivity, 100%). Positive results were obtained only with tuberculosis patients. For diagnostic specimens from untreated patients, the mean time to achieve a GI of 10 was 6 days.