Comparison of two automated systems for the isolation of mycobacteria from clinical specimens

The Bactec MGIT 960 (Becton-Dickinson, The Mycobacterial Growth UK) automated mycobacterial liquid culture system system (Becton-Dickinson) was compared with the Bactec 9000 MB (Becton-Dickinson) in order to assess ease of use, diagnostic reliability and safety features. One thousand twenty-nine clinical specimens were cultured in parallel, yielding a total of 125 (12.1%) mycobacterial isolates, including 71 Mycobacterium tuberculosis and 18 Mycobacterium avium. The Bactec MGIT 960 demonstrated a mycobacterial recovery rate and speed of detection equivalent to that of the Bactec 9000 MB for clinically important isolates. The Bactec MGIT 960 integrates smoothly into laboratory workflow, does not require needle inoculation and has a much larger capacity than Indicator Tube (MGIT) uses Middlebrook 7H9 broth (4ml in glass bottles) and the same oxygen-quenching fluorescence technology as the Bactec 9000 MB in a manually read system [4, 5]. Its diagnostic reliability compares favourably with existing solid and liquid culture systems, but the procedure is labour-intensive [6-9]. The Bactec MGIT 960 is a completely automated culture system, employing Middlebrook 7H9 broth (7 ml) in a machine that has a much larger capacity than other automated culture systems (960 bottles vs. 240 bottles) [G, Daeschlein, K, Lange: European Congress of Clinical, Microbiology and Infectious Diseases, 1999, Abstract no. P 0044].