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

BACKGROUND: 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.

MATERIALS AND METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.