Species and Genetic Diversity of Nontuberculous Mycobacteria (NTM) in Suspected Tuberculosis Cases in East Azerbaijan, Iran: A Cross-sectional Analysis

Abstract Introduction The outbreak of nontuberculous mycobacterial (NTM) infections has increased worldwide, attracting attention in routine diagnostic settings, particularly among patients with suspected tuberculosis. This study aimed to acquire knowledge of NTM infections in patients with suspected tuberculosis and to evaluate the genetic diversity of the strains. Methods In this study, 230 clinical specimens were collected from suspected tuberculosis patients. Following decontamination with N-Acetyl-L-cysteine–sodium hydroxide (NALC-NaOH), the sediments of specimens were inoculated onto Löwenstein–Jensen medium and then incubated at 30°C for 8 weeks. The samples that yielded positive cultures underwent evaluation through sequencing conserved fragments of IS6110 and hsp65 . For those samples that were not identified as part of the M. tuberculosis complex (MTC) by IS6110 PCR, further analysis was conducted using PCR to detect fragments of the hsp65 gene. Results Twenty-one NTM species were isolated from 230 clinical specimens (14 NTM from pulmonary specimens and 7 from extrapulmonary specimens). Among these, 12 (57.14%) were rapid-growing mycobacteria (RGM) and 9 (42.85%) were slow-growing mycobacteria (SGM). No M. avium complex (MAC) was identified in any of the specimens. Notably, M. kansasii, M. gordonae , and M. abscessus strains exhibited significant genetic diversity. Conclusions The prevalence of infections attributed to nontuberculous species surpasses that of tuberculosis. These findings underscore the importance of exploring NTM species in individuals suspected of having TB.