Genetic Variation of the Mycobacterium tuberculosis in North of Iran; the Golestan Province

Background: Genotyping of Mycobacterium tuberculosis (M.tub) is an essential step for several purposes, including the epidemiological studies and the tuberculosis (TB) control programs. Golestan province in the Southeast of the Caspian Sea is the second Iranian high burden TB province. Objectives: This study aimed to determine the genetic diversity of M.tub isolates in Golestan province located in the north of Iran. Methods: In this cross-sectional study, all non-repetitive confirmed M.tub isolates, which were collected from patients with TB in Golestan province in 2016, were used for genotyping. After DNA extraction, PCR was done for 15 loci of mycobacterial interspersed repetitive unit-variable-number of tandem repeats (MIRU-VNTRs) for the 162 M.tub isolates. Then genetic diversity and genetic relationships between them were assessed by best match analysis using tools on MIRU-VNTRplus database. Antibiotic susceptibility patterns of M.tub isolates was determined by the proportional method. Statistical analysis was done by SPSS and R software. Results: Out of 162 M.tub isolates, 156 genotype patterns were obtained, which 150 of which were unique. Nine of 15 loci were highly discriminative. The clustering rates were 3.7%. The prevalence of polyclonal infection was 2.46%. Also, HGDI and AHGDI were 0.999 and 0.979, respectively. The New-1 (22.2%) and Beijing (13.6%) sub-lineages had the highest prevalence in this region. Although there was no significant correlation between demographic criteria and M.tub genotypes, still Beijing isolates showed more treatment failure (18.2% vs. 0.7%)andresistance to streptomycin (40.9% vs. 7.8%)comparedto others (P< 0.05). The assessment of theminimum spanning tree showed that the members of the clonal complex were limited except for membersof Beijing. The PCA analysis showed that the combination of Qub11b and Mtub30 loci was diagnostic for Beijing sub-lineage. Conclusions: Owing to the high genotypic diversity of M.tub isolates in this region, relying on tuberculosis control program just based on close contact treatment is not sufficient, and we require to apply another approach.