STRAINS OF MYCOBACTERIUM-TERRAE COMPLEX WHICH REACT WITH DNA PROBES FOR MYCOBACTERIUM-TUBERCULOSIS COMPLEX

Following a recent report that two isolates of Mycobacterium terrae co mplex had given positive reactions with M. tuberculosis complex DNA pr obes, a joint study was undertaken to determine the extent of these fi ndings in the clinical culture collection holdings of two state health laboratories. A total of 117 M. terrae complex strains (identified by standard biochemical methods) were subjected to M. tuberculosis compl ex probe testing with the two then-available kits (from Syngene, Inc., and Gen-Probe, Inc.). In addition to the two original isolates first reported, two further M. terrae complex isolates were found to react w ith the M. tuberculosis complex probes. Two modifications of the Accup robe (Gen-Probe, Inc.) test method were evaluated. Extension of the se lection time to 8 min was the most convenient modification and rendere d the M. terrae complex isolates negative when tested with the Accupro be M. tuberculosis complex probe. However, the effects of increased se lection time on the overall sensitivity of the M. tuberculosis complex probe require further study.