Comparative evaluation of PCR and commercial DNA probes for detection and identification to species level of Mycobacterium avium and Mycobacterium intracellulare

Abstract

Selective amplification of a 187-bp fragment within the DT6 sequence using the AV6 and AV7 primers for Mycobacterium avium and of a 666-bp fragment within the DT1 sequence of Mycobacterium intracellulare, using the IN38 and IN41 primers was performed for 69 clinical isolates identified as M. avium complex by conventional methods. The results were compared in parallel with results with commercial M. avium and M. intracellulare probes. A positive response to either of the two PCRs or M. avium-M. intracellulare AccuProbes constituted positive detection as M. avium complex; this cumulative detection limit was 94.2% for PCR, compared with 90% for AccuProbe. Concordance, on the other hand, was considered an identical species identification using either DT1 PCR and the M. intracellulare probe or DT6 PCR and the M. avium probe. In this investigation, 90% of isolates gave concordant results. We conclude that DT6 and DT1 PCRs are inexpensive and at least equally sensitive, in-house options to the AccuProbe system for species identification of M. avium and M. intracellulare.