Genotyping of rifampin-resistant Mycobacterium tuberculosis isolates from western Turkey

BACKGROUND: Although the rate of multiple drug resistance is high, there is no published data on the transmission rate of drug-resistant strains of Mycobacterium tuberculosis in the Aegean region of western Turkey that are based on molecular methods. METHODS: IS6110 and pTBN12 restriction fragment length polymorphism (RFLP) methods were used for typing M. tuberculosis strains isolated from 26 sputum samples from 26 patients. RESULTS: Nineteen of the rifampin-resistant isolates (73.1%) contained 6 to 11 copies of IS6110. Eighteen different IS6110 DNA fingerprint patterns were observed in the 26 rifampin-resistant isolates. Twenty-three of the 26 rifampin-resistant isolates were also resistant to isoniazid. When evaluated together, both methods yielded 21 (80.9%) different banding patterns and the level of clustering was 34.6%. The average number per pattern was 1.23 (26/21). CONCLUSIONS: IS6110 fingerprinting suggests that the rifampin-resistant isolates obtained from the Aegean region had a relatively high clustering rate and were clonally related. These findings showed that the rifampin-resistant isolates are actively transmitted between patients. Urgent measures should be taken to prevent the spread of these resistant strains.