Molecular Identification, and Characterization of Mycobacterium kansasii Strains Isolated from Four Tuberculosis...

Non-tuberculous mycobacterial (NTM) infections are growing concern in many countries around the globe including Iran. Among them, Mycobacterium kansasii (M. kansasii) causes both pulmonary and extra-pulmonary infections. Despite the high prevalence of M. kansasii isolates in Iran, unfortunately little is known about the epidemiological aspects of M. kansasii infection. Hence, the aim of the present study was to investigate the molecular identification, determination of subtypes variation and geographic distribution of clinical isolates of M. kansasii isolates.

In the present study, 108 clinical pulmonary isolates suspected to NTM were collected from four Tuberculosis Regional Reference Laboratories in Iran during 2016-2018. The isolates were confirmed as NTM using conventional and molecular methods. Among them, M. kansasii isolates were subjected to rpoB gene sequencing. For determination of subtyping of M. kansasii isolates, polymerase chain reaction-restriction enzyme analysis (PCR-REA) based on the hsp65 gene was performed.

Based on the rpoB gene sequence analysis, 33 (30.5%) isolates were identified as M. kansasii species, compared to 31 (28.7%) isolates using phenotypic methods. The subtype I was the most frequent subtype (n=24; 72.7%), followed by subtype II (n=8; 24.2%).

We indicated that the rate of M. kansasii isolation with clinical significance appears to be increasing in Iran, especially in highly industrialized cities. The high rate of M. kansasii subtype I may suggest that this genotype has a particular potency for colonization, and a higher epidemiological potential for causing infection in humans. More studies are needed to provide a better understanding of the biology and pathogenicity of M. kansasii subtype I.