Genetic Diversity of Drug-resistant Mycobacterium tuberculosis Isolates in Isfahan Province of Iran

Background: Increasing drug resistance is an important factor in the complexity of tuberculosis (TB) control. The identification of disease transmission type, recurrence of a previous infection, or new transmission of the disease is the key factor in the control of TB. In this study, we aimed to identify the genetic diversity of drug-resistant Mycobacterium tuberculosis isolates in Isfahan province of Iran through the mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing method based on 24 loci.

Materials and methods: Of 300 isolates obtained from a variety of clinical specimens, 18 drug-resistance M. tuberculosis clinical isolates (resistant to a single drug to more than one drug) were collected between 2013 and 2015 from regional TB reference laboratory in Isfahan. All drug-resistance M. tuberculosis isolates were typed by 24-locus MIRU-VNTR typing.

Results: The highest percentage of isolates, 38.8%, belonged to the East-Asian lineage (lineage 2), while the lineages Indo-Oceanic (lineage 1), East-African-Indian (lineage 3), and Euro-American (lineage 4) represented 5.5%, 22.2%, and 33.3%, respectively. Among the 33.3% (6/18) Euro-American strains, the Latin American- Mediterranean and Ural sub-lineage were 22.2% (4/18) and 11.1% (2/18), respectively.

Conclusion: The results of this study show that the lineages of drug-resistant M. tuberculosis isolates in Isfahan province of Iran are similar to those reported in the Eastern Mediterranean region (indicative of the epidemiological relationship between the countries in the region). Continued molecular monitoring is important as it has been proposed that the genetics and evolutionary backgrounds of drug-resistant M. tuberculosis strains may have an impact on the transmissibility profile.