Direct detection of Mycobacterium tuberculosis complex and M. avium complex in tissue specimens from cattle through identification of specific rRNA sequences.

Mycobacterium Tuberculosis Direct test and Accuprobe M. avium Complex test, rely on recognition of specific rRNA sequences. The present investigation included sequentially a pre-evaluation study and a study on non-visible lesion tuberculin reactor cattle. As regards the first study, tests were performed on tissue samples from 14 reactors with tuberculous-like lesions and from as many lesion-free non-reactors, using culture findings as a reference. MTD and Accuprobe M. Avium Complex tests proved positive in 12 and 2 reactors respectively. Both tests proved negative in all non-reactors. Data consisted with culture findings. The aim of the second study was to verify the presence of mycobacteria in lymph node and tonsil homogenates from 32 non-visible lesion cattle. MTD and Accuprobe M. avium Complex test proved positive in 10 and 14 subjects respectively; no overlap was found. Our research demonstrates that low to minimal amounts of the main pathogenic mycobacteria can be reliably identified from cattle tissues by commercially available tests, which give simple, more rapid results than conventional techniques.