Molecular epidemiology of multidrug-resistant Mycobacterium bovis isolates with the same spoligotyping profile as isolates from animals.

PCR-based characterization techniques have been adopted in most laboratories for Mycobacterium bovis typing. We report a molecular characterization of human multidrug-resistant M. bovis isolates and three bovine isolates that share the spoligotyping profile. The analysis of the direct repeat region showed that both groups differed in the presence of spacers not included in the current membrane. They were also distinguished by two out of the nine mycobacterial interspersed repetitive unit variable-number tandem repeat loci tested, indicating that the human infection was not acquired from the cattle from which isolates were obtained. These results highlight that a combination of techniques is required for appropriate discrimination, even for those spoligotypes that have a low frequency.