Evaluation of the MB/BacT system compared with Middlebrook 7H11 and Lowenstein-Jensen media for detection and recovery of mycobacteria from clinical specimens

Abstract

MB/BacT vials (an automated system), Middlebrook 7H11 agar plates with the microcolony method for growth detection, and conventional Lowenstein-Jensen egg-based medium were assessed for their rates of recovery, time to detection and ease in aiding the identification of mycobacterial isolates. Of the 2101 consecutive, non-selected specimens for tuberculosis analysed in the laboratory, 158 (7.5%) yielded growth of 159 mycobacteria on at least one of the three media, comprising 111 Mycobacterium tuberculosis and 48 non-tuberculous mycobacteria. Of the 111 specimens positive for M. tuberculosis, 100 isolates were recovered from MB/BacT vials, 99 from M7H11 agar plates, and 86 from Lowenstein-Jensen tubes. The combination of MB/BacT and M7H11 recovered 110 isolates of M. tuberculosis, 107 from M7H11 and Lowenstein-Jensen, and 105 from MB/BacT plus Lowenstein-Jensen. The average time to detection of M. tuberculosis was 11 days with M7H11 using the microcolony method, 16 days with MB/BacT, and 19.5 days with the conventional Lowenstein-Jensen method. The MB/BacT vials recovered greater numbers of non-tuberculous mycobacteria than either of the other two media, but these were considered mostly to be saprophytes. It was concluded that a combination of media was better than a single medium. None of the media combinations showed statistical differences. Use of M7H11 with the microcolony method, which shortens the detection time for mycobacteria and facilitates the detection of mixed cultures, together with the Lowenstein-Jensen tube, was a useful combination.

A systematic review of rapid diagnostic tests for the detection of tuberculosis infection

“…The media are either egg-based [e.g. Lowenstein-Jensen (LJ) 76,77 and Ogawa media 78 ] or agar-based (Middlebrook 7H9, 7H10 and 7H11 77 ). Media are assessed for rate and appearance of growth of mycobacteria.…”

“…In eight studies Accuprobe was performed only on AFBpositive samples. One study 120 used PCR restriction fragment length polymorphism analysis on all isolates and one 76 used the AMTD test.…”

HIV and tuberculosis in India

“…Automated liquid culture systems that detect bacterial CO 2 production or O 2 consumption with radiometric (BACTEC), fl uorescent (MGIT), colorimetric (MB/BacT system) or pressure sensors (ESP culture system II) roughly halve the time to detection and are being evaluated for use in resource-poor settings (Williams-Bouyer et al 2000; Lee et al 2003;Gil-Setas et al 2004). Molecular assays have been developed for rapid detection of growth as well as species identifi cation and drug susceptibility testing.…”

Detection of Mycobacterium marinum in clinically asymptomatic Siamese fighting fish (Betta splendens) from ornamental fish shops in Chiang Mai Province, Thailand

“…from Löwenstein-Jensen medium (28 samples) was higher than from Middlebrook 7H10 medium (7 samples). However, previous reports indicated no significant difference in the recovery rates from these culture media [16,17]. Morover, conventional bacterial culture methods used to diagnose Mycobacterium spp.…”