Beijing strains of Mycobacterium tuberculosis in smear‑positive tuberculosis patients in North‑West and West of Iran

Tuberculosis (TB) is the leading cause of morbidity and mortality among chronic infectious diseases. The goal of this cross‑sectional study (2012–2014) was to examine the prevalence of Mycobacterium TB (MTB) Beijing strains in regions near the Iranian border and to identify any epidemiological links.

To this end, MTB isolates were harvested, from 64 HIV‑negative, pulmonary smear‑positive TB patients from the Iranian border provinces of East Azerbaijan (North‑West), Kurdistan (West), and Kermanshah (West) (2012–2014). Isolates were subjected to restriction fragment length polymorphism (RFLP) analysis, using the insertion sequence IS6110 as a probe (IS6110 RFLP), and drug susceptibility testing by the proportion method. We gathered demographic and clinical data using a questionnaire and reviewing patient records. Results were analyzed with Gel Compare II 6.6 and SPSS‑18.

The mean age of the patients was 54.4 years and 46.9% were male. The prevalence of Beijing strains among the isolates was 9.4% (17.6% in the Western provinces and 0% in East Azerbaijan). There was a statistically significant relationship between the Beijing strains and drug resistance and also between these strains, and the recurrence of TB in patients that had previously received treatment (P = 0.02 and P = 0.04, respectively).

Finally, the prevalence of Beijing strains in Western Iran was greater than expected. Our results therefore indicate that regional and cross‑border tracing may be necessary to control spread of this organism.