A Report on Drug Resistance Patterns of <i>Mycobacterium tuberculosis</i> Isolates in Northern Iran

BACKGROUND: (MTB) drug resistance in regions located at the proximity of the Caspian Sea. We aimed to assess the drug resistance patterns of the MTB isolates to anti-tuberculosis drugs in patients from four northern provinces of Iran between April 2013 and March 2019. METHODS: Drug susceptibility testing (DST) was performed by culturing MTB isolates on the Lowenstein-Jensen medium using the proportion method. RESULTS: Out of 963 MTB isolates, 927 (96.3%) were recovered from Iranian cases and 36 (3.7%) were from Afghan immigrants. Based on DST, 59 (6.1%) showed any drug resistance pattern, while 18 patients (1.9%) were multidrug-resistant (MDR) or rifampicin-resistant (RR). Resistance to streptomycin (STR), isoniazid (INZ), rifampicin (RIN), and ethambutol (ETL) was reported in 33 (3.4%), 28 (2.9%), 18 (1.9%), and 12 isolates (1.2%), respectively. CONCLUSION: The rate of MDR/RR in four northern provinces of Iran was in line with previous reports from the World Health Organization. Due to proximity to the former Soviet Union, which had a high rate of MDR/RR isolates, the establishment of cross-border tuberculosis (TB) control strategies is recommended to reduce the possibility of MDR-TB transmission. Moreover, DST for all TB cases is recommended as an effective diagnostic tool for optimal monitoring and control of drug resistance in these areas. Future studies with a molecular epidemiology approach will be needed to evaluate the transmission dynamics of MTB in these regions.