Comparison of fluorescent BACTEC 9000 MB system, Septi-Chek AFB system, and Lowenstein-Jensen medium for detection of mycobacteria

Abstract

The newly developed fluorescent BACTEC 9000 MB system for automated culture of mycobacteria was compared with the Septi-Chek AFB system and Lowenstein-Jensen medium (LJ). A total of 2,005 clinical specimens were included in the study. Mycobacteria were isolated from 202 (10.1%) specimens, including 155 Mycobacterium tuberculosis complex isolates and 47 Mycobacteria other than M. tuberculosis isolates. Of 131 isolates detected by the BACTEC system, the Septi-Chek AFB system, or both, 120 (91.6%) were detected by the BACTEC system and 105 (80.2%) were detected by the Septi-Chek AFB system (P < 0.02). The recovery rate in the BACTEC system compared with that in the Septi-Chek AFB system was significantly higher for M. tuberculosis complex isolates (P < 0.005) and for isolates from acid-fast smear-negative specimens (P < 0.01). Of 148 isolates detected by the BACTEC system, LJ, or both, 142 (95.9%) were detected by the BACTEC system and 118 (79.9%) were detected by LJ (P < 0.001). The recovery rate in the BACTEC system compared with that on LJ was significantly higher for M. tuberculosis complex isolates (P < 0.001). The BACTEC system detected more mycobacteria from both smear-positive and smear-negative specimens than LJ. The mean times to detection of mycobacteria were 17.6 days for the BACTEC system, 26.0 days for the Septi-Chek AFB system, and 29.4 days for LJ. The BACTEC fluorescent 9000 MB system is a rapid, sensitive, and efficient method for the isolation of mycobacteria.