RESUMO
The present study investigated the role in transmission of M. tuberculosis strains isolated from tuberculosis patients residing in Northwest [East and West Azarbaijan] of Iran. We performed restriction fragment length polymorphism analysis on IS6110 of M. tuberculosis isolated from Northwest Iran. Total of 165 isolates of M. tuberculosis were analyzed by RFLP method. The 5 copies and more IS6110 isolates comprised 30.52% of the total isolates. They formed 16 clustered groups consisting of 2 to 10 cases each. 69.48% of patients had a unique RFLP patterns. Cases from male patients were more clustered than female patients but statistically was not significant [P>0.05]. In this study patients with 56 and older age were strongly associated with clustering [59.6%], which were significantly more than younger patients [P<0.05]. In the present study we found old age as a major risk factor in contact dependent transmission of TB compared to disease recurrence. Unemployment and poor living condition were also among the risk factors in transmission of tuberculosis