Direct identification of Mycobacterium species in BACTEC 7H12B medium by high-performance liquid chromatography.

Primary cultures of mycobacteria grown in BACTEC 7H12B medium (Becton Dickinson and Co., Paramus, N.J.), with and without the addition of oleic acid-albumin-dextrose-catalase (OADC) enrichment (Becton Dickinson and Co., Cockeysville, Md.), were analyzed for their mycolic acid patterns by high-performance liquid chromatography. Of the 126 isolates grown in medium to which OADC was added, 117 (93%) were successfully identified to the species level. The time to identification of Mycobacterium tuberculosis (n = 65) averaged 19 days, and the average time was 21 days for nontuberculosis mycobacteria (n = 52) from initial specimen processing. None of the 10 isolates cultured without OADC were identified. The mycolic acid patterns were considered reliable for identification if the height of the tallest peak in the chromatogram was at least 50% of the internal standard peak height.