Background and Aim: The present study investigates epidemiological diversi ty among Mycobacterium tuberculosis strains circulating in the Northeast of Iran using 12 - loci MIRU - VNTR and spoligotyping.
Methods: This study was performed on 140 M. tuberculosis strains selected from the sputum of new cases of pulmonary tuberculosis (TB) patients in three Khorasan provinces of Iran. 12 loci MIRU - VNTR and Spoligotyping were performed in all isolates.
Results: By MIRU - VNTR analysis, 76 distinct patterns comprising of 19 clusters and 57 unique patterns were identified. Based on the results, MIRU10, MIRU 26 and ETRF were highly discriminative. By Spoligotyping analysis, 103 isolates (73.6%) were classified into 14 clusters con taining 2 – 56 isolates and the remaining 37 isolates (26.4%) were unique patterns. By combining two techniques, 94 distinct patterns (15 clusters) contained 61 isolates (43.6%), and 79 unique patterns were identified. The discriminatory power (HGDI) of comb ination of two techniques was 0.962 which was higher than that of each technique alone. With trees designed by Bionumerics software, we were able to differentiate isolates with similar genetic patterns and to group them together. Two of our great close clu sters were Haarlem and CAS lineage. In this study, all strains with MDR and combined (INH + RIF) resistance were related to Beijing strains. . Also, homoplasy was observed in a number of patterns.
Conclusion: The results showed that in molecular typing of MTB, using the two methods of “Spoligotyping” and “MIRU - VNTR” simultaneously could increase the genetic patterns of MTB strains in a much effective way compared to using only one method.