COMPARISON OF GENUS-SPECIFIC AND SPECIES-SPECIFIC PROBES FOR PCR DEFECTION OF MYCOBACTERIAL INFECTIONS

We describe experiments comparing use of different DNA probes to detec t mycobacteria in clinical specimens after PCR. The objective was to a ssess correlation between results using Mycobacterium genus-specific, and species-specific M. tuberculosis probes. Given sufficient concorda nce, sequential use of such probes would provide a useful screening to ol. An evaluation of genus-specific probes compared use of repetitive sequences in the clone pMAv17 with the 65-kDA sequences. Sensitivity w as 100% for pMAv17, 93% using the 65-kDA sequence; specificity was 70% for both. We then compared M. tuberculosis-specific probes developed by us (Tb400) with IS6110 and mpt40. Sensitivity using Tb400 was 100%; using IS6110 was 97%, and using mpt40 was 50%. Specificity using Tb40 0 and IS6110 was 68%, and was 70% using mpt40. Fourteen specimens whic h were PCR-positive and culture-negative, were positive using both gen us probes, and the M. tuberculosis-specific probes Tb400, and IS6110. Ten of these were positive using mpt40.