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.The Mycobacterium tuberculosis complex (MTBC) consists of a group of closely related Mycobacterium species, including M. tuberculosis, M. bovis, M. africanum, M. microti, and M. caprae. These species are the primary cause of tuberculosis in humans, and they also infect wild and domesticated animals. The close interrelatedness of these species has been demonstrated by DNA-DNA hybridization, multilocus enzyme electrophoresis, and sequencing of the 16S rRNA genes and the 16S-23S rRNA gene internal transcribed spacers (12,16).However, the epidemiology, host range, pathogenicity, geographic distribution, and drug resistance of these species are quite different (12,16,22). Different species display different phenotypic characteristics according to conventional biochemical tests. Because differentiation of species in the MTBC by these methods is labor-intensive, time-consuming, and dependent on sufficient bacterial growth, these tests may not be performed routinely in every laboratory (19,23). Therefore, various molecular methods have been used for differentiation, such as DNA sequencing (i.e., gyrB and hsp65) and PCR amplification of regions of differences (RDs) or spoligotyping (9,11,26,29,30). Although they are rapid and more accurate than the conventional methods, such procedures usually require specialized molecular laboratories and technical experience (22,26,29).In this study, our goal was to determine the distribution of consecutive MTBC isolates at the species level from 2007 to 2010 in one of the largest research and training hospitals in Istanbul. We also wished to investigate the current status of bovine tuberculosis in Turkey. To our kn...