DEMONSTRATION OF HOMOLOGY BETWEEN IS6110 OF MYCOBACTERIUM-TUBERCULOSIS AND DNAS OF OTHER MYCOBACTERIUM SPP

The insertion sequence IS6110 has an important role in diagnostic PCR and typing of Mycobacterium tuberculosis. We have evaluated a one-tube nested PCR which detects IS6110. Positive results were obtained with DNAs from four of four M. tuberculosis isolates, seven of eight M. fortuitum isolates, four of seven ill. avium-M. intracellulare complex isolates, four of five M. kansasii isolates, five of five M. xenopi isolates, two of four il M. malmoense isolates, and two of two M. chelonei isolates. These results were confirmed by hybridization of genomic DNA from bp 505 to 685 of the IS6110 from nl. tuberculosis H37Rv. Dot blot hybridization of genomic DNAs from these isolates with the same probe confirmed the presence of a homologous sequence In these mycobacterial species. These data suggest that false-positive results may be obtained for clinical samples when some methods based on IS6110 are used.