Identification by spoligotyping of a caprine genotype in Mycobacterium bovis strains causing human tuberculosis

We have used spoligotyping to characterize 18 Mycobacterium bovis strains isolated from cattle and 23 M. bovis strains isolated from goats. The spoligotypes revealed that caprine strains form a separate and well-differentiated group that we refer to hereafter in this abstract as the caprine genotype. To evaluate the importance of this genotype as a cause of tuberculosis in other animal species, including humans, we applied the spoligotyping method to 112 strains, including to all isolates identified as M. bovis by a Mycobacterial National Reference Laboratory (Majadahonda, Madrid) from 1994 to 1996. Eighty-three of these strains were identified in human isolates. In addition to being identified in three goat isolates and two sheep isolates, the caprine genotype was also found in three isolates causing human tuberculosis. Evidence to support the argument that there is a zoonotic risk of caprine tuberculosis was presented by the identification of the caprine genotype in an isolate from a veterinary worker with a recent history of contact with tuberculous goats.