Species Distribution of the Mycobacterium tuberculosis Complex in Clinical Isolates from 2007 to 2010 in Turkey: a Prospective Study

The Mycobacterium tuberculosis complex (MTBC) consists of a group of closely related species that differ in their epidemiological profiles, host ranges, pathogenicities, geographic distributions, and drug resistances. Identification of members in the MTBC is essential for monitoring the epidemiology of tuberculosis (TB) and implementing appropriate public health control measures. In this study, 188 consecutive MTBC clinical isolates from 2007 to 2010 were evaluated to determine the prevalence of MTBC species in Turkey. PCR and restriction fragment length polymorphism analysis (PCR-RFLP) of the gyrB gene were used, and results for species other than M. tuberculosis were confirmed using the GenoType MTBC assay (Hain Lifescience, Nehren, Germany). Most of the strains were found to be M. tuberculosis (94.1%). The prevalences of M. bovis and M. caprae were 4.3% and 1.6%, respectively. Only one M. bovis BCG strain was identified. Overall, the frequency of bovine tuberculosis in humans was 5.3%. We had assumed that bovine TB infection was under control in animal herds, but primary M. bovis infections in humans caused by transmission from infected animals are still an issue in Turkey. Our results indicate that the frequent identification of M. bovis in routine mycobacteriological laboratory work has further importance due to the well-known resistance of this species to pyrazinamide.