[Reactivities of various mycobacteria species against DNA probes (Gen-Probe Rapid Diagnostic System) specific to Mycobacterium tuberculosis complex, Mycobacterium avium and Mycobacterium intracellulare]

Abstract

Various mycobacterial species (22 species, 178 strains) were studied for their reactivity to DNA probe specific for Mycobacterium tuberculosis complex (MTC), M. avium or M. intracellulare, using Gen-Probe Rapid Diagnostic System (Gen-Probe Inc., San Diego, Calif., U.S.A.). All the MTC strains, including M. tuberculosis, M. africanum, M. bovis and M. microti reacted with MTC-DNA probe at the % hybridization value of 42.8-51.9% (values higher than 10% are regarded as positive), but their reactivity to MAC-DNA probes (0.8-2.5%) was under the cut off value (10%). The test strains (28 strains) of M. avium complex (MAC) segregated into two groups on the basis of reactivity to DNA probes specific for M. avium and M. intracellulare, that is, one group (16 strains) positively reacted with M. avium-probe but not with M. intracellulare-probe, and the other group (12 strains) showed the converse reactivity. The two groups did not show a reactivity with MTC-probe higher than the cut off value. Nontuberculous mycobacteria other than MAC, including M. kansasii, M. marinum, M. simiae, M. asiaticum, M. scrofulaceum, M. gordonae, M. szulgai, M. malmoense, M. xenopi, M. gastri, M. nonchromogenicum, M. terrae, M. triviale, M. fortuitum, and M. chelonae (subsp. abscessus and chelonae) reacted with neither MTC- nor MAC-probe and values for % hybridization (0.6-3.6%) were lower than the cut off value. These findings indicate extremely superior specificity of the DNA probes (Gen-Probe) for MTC, M. avium and M. intracellulare, thereby indicating the usefulness of Gen-Probe Rapid Diagnostic System for the MTC and MAC in clinical use.