Genetic diversity of Mycobacterium tuberculosis isolates from tuberculosis patients in northwestern Iran by MIRU-VNTR method during 2016-2019

Abstract

Mycobacterium tuberculosis is the cause of tuberculosis (TB) which is one of the leading causes of death from infectious diseases worldwide. Due to the latent infection of tuberculosis, classical methods cannot determine the prevalence of the disease. Today genotyping methods are based on random duplicate sequences (VNTR) scattered mycobacterium repetitions units (MIRU). This method is based on PCR and the number of repetitions of each locus is calculated based on the PCR product size.

Methods and materials: 120 isolates of Mycobacterium tuberculosis were collected from pulmonary tuberculosis patients from the tuberculosis center of Tabriz province and because the collected samples were negative in the period of September 2016 to March 2019 and lacked the DNA genome, we were forced to collect the samples in our study and the duration of collecting the samples from November 2020 to April 2021 were performed from the tuberculosis center of Tabriz province. they were cultured in a specific medium and then extracted by chloroform-CTAB fever method and transferred to the microbial laboratory of the Center for Applied Pharmaceutical Research in isolation. The 15 genetic locus patterns of MIRU isolates were evaluated to determine their genotyping and phylogenetic relationship using PCR method.

Results: DNA was extracted from 120 isolates of Mycobacterium tuberculosis collected from patients including 78(65%) males and 39(32/5%) females and random replications were evaluated by multiplex method. MIRU-VNTR results showed that patients had 15 clusters and 36 unique patterns that the number of isolates in these clusters included: on cluster with 7 members, two cluster with 5 members, 4 clusters with 3 members, 8 clusters with 2 members and our 15 clusters have 45 patients. the number of Azerbaijan patients in our study was 3 (2/5%) and average age of patients was 62 years.