Genetic Lineages of Mycobacterium tuberculosis Isolates in Isfahan, Iran

Abstract

In this study, we aimed to identify the genetic lineages of Mycobacterium tuberculosis isolates in Isfahan via the mycobacterial interspersed repetitive-unit-variable number tandem repeat typing method based on 15 loci. Forty-nine M. tuberculosis isolates were collected between 2013 and 2015 from Tuberculosis patients in Mollahadi Sabzevari Tuberculosis Center in Isfahan. All isolates were typed by 15-locus MIRU-VNTR typing. The highest percentage of isolates, 44.89 % (22/49), belonged to the Euro-American lineage, while the frequencies of the East-African-Indian, East-Asian, and Indo-Oceanic lineages were 28.57 % (14/49), 24.4 % (12/49), and 2.04 % (1/49), respectively. Among the 22 isolates of the Euro-American lineage, those belonging to the NEW-1 sub-lineage were most prevalent (24.4 %). Approximately, the same proportion of isolates belonging to the Delhi/CAS, Beijing, and NEW-1 sub-lineages were identified in Iranian and Afghan immigrant patients. The Delhi/CAS and Beijing sub-lineage isolates were prevalent among patients who had been previously treated for TB. Results showed that all of the 49 MIRU-VNTR patterns were unique and the clustering rate of the 15-locus MIRU-VNTR was 0.0 (minimum recent transmission). The results of this study show that the lineages of M. tuberculosis isolates in Isfahan are similar to those reported in the Eastern Mediterranean region (indicative of the epidemiological relationship between the countries in the region). The low clustering rate in our results reveals that transmission of tuberculosis in Isfahan is, in most cases, a reactivation of previous tuberculosis infection and the role of recently transmitted disease is minor.