IS6110 fingerprinting of Mycobacterium tuberculosis strains isolated from Northwest of Iran

Abstract

IS6110-based DNA fingerprinting is currently the most widely used genetic marker for differentiating among Mycobacterium tuberculosis strains. To evaluate the DNA polymorphism among Mycobacterium tuberculosis strains and to determine if there is matching of IS6110 fingerprints representing recent transmission of tuberculosis. Totally one hundred and sixty five isolates of M. tuberculosis (53 from West Azarbaijan and 112 from East Azarbaijan) were analyzed by IS6110 restriction fragment length polymorphism fingerprinting. Isolates having identical RFLP patterns were considered a cluster. The average number of IS6110 copies per strain was 7.3 and ranged from 0 to 17 among the M. tuberculosis isolates. The IS6110-DNA patterns from these isolates were highly polymorphic. In conclusion 123 patterns were observed which 16 patterns were shared by 47 isolates (30.52%). Most strains (93.62%) had multicopy patterns and only 3 of clustered isolates had less than six IS6110 copies. In our study increased clustering was observed with isolates from male patients. RFLP analysis of 154 isolates of M. tuberculosis showed a considerable diversity, suggesting that most patients were infected with unique strains, probably resulted from reactivation of the latent infection. é 2007 Academic Journals Inc.