Comparison of the genetic convergence between myco-bacterium strains by three RFLP-based methods in central province of Iran

The utilization of molecular techniques in the epidemiology of tuberculosis have provided an opportunity for using effective markers to trace the transmission of the disease. The purpose of this study was to compare the genetic patterns of Mycobacterium tuberculosis by three methods of RFLP technique. In a cross-sectional and prospective study, 95 strains of M. tuberculosis isolates were selected for DNA fingerprinting. Extraction of DNA from Mycobacterium strains and DNA fingerprinting with IS-6110, PGRS and DR probe were performed by standard protocols. Overall, the diversity of RFLP among 95 tuberculosis patients were 48, 50 and 45 on the basis of IS6110, PGRS and DR patterns, respectively. Twenty of these patterns (21.1%) with IS6110-RFLP, twenty-two (23.2%) with PGRS-RFLP and seventeen (17.9%) with DR-RFLP occurred with unique RFLP patterns, whereas the remaining 28 patterns were communal. The risk factors of clustering among tuberculosis patients were age < 45 years, new cases, degree of sputum smear ≥ 2+, and close contact. Our study demonstrated that IS6110-RFLP, PGRS-RFLP and DR-RFLP genotyping could roughly identify similar proportions of clustered (secondary) cases as well as the same risk factors for clustering.