Molecular Diversity of Mycobacterium tuberculosis Strains in Northwestern Iran

BACKGROUND Years after the development of antituberculosis (TB) drugs, many people continue to suffer from this disease. To control the spread of TB, strains of the Mycobacterium tuberculosis complex need to be determined, and sources of infection must be identified. Such steps should help to prevent transmission of the infection. OBJECTIVES The aim of this study was to perform molecular genotyping of isolates of the M. tuberculosis complex obtained from patients in northwestern Iran. METHODS One hundred ninety-four culture-positive M. tuberculosis isolates obtained from patients in northwestern Iran were analyzed using the mycobacterial interspersed repetitive unit-exact tandem repeats (MIRU-ETR) method. RESULTS The MIRU-ETR method distinguished 162 different patterns in the 194 isolates, comprising 23 clusters and 139 unique patterns. Its discriminatory power according to the Hunter-Gaston discriminatory index (HGDI) was 0.9978. The largest cluster contained six isolates. CONCLUSIONS This research indicated that various strains of M. tuberculosis were responsible for TB and that the majority of cases were due to reactivation.