| Summary: | <p>Abstract</p> <p>Background</p> <p>A high proportion of pigs imported to Serbia from a Lithuanian breeding herd reacted positively against avian and/or bovine tuberculin. The pigs were euthanized and lesions characteristic for mycobacterial infection were detected. An investigation of potential mycobacteriosis in the pigs imported to Serbia and the possible source of infection in the Lithuanian herd were therefore initialised.</p> <p>Results</p> <p>Formalin fixed, paraffin embedded lymph nodes from tuberculin positive animals were examined by real-time PCR for IS<it>1245 </it>and IS<it>6110</it>. IS<it>1245 </it>was detected in 55% and IS<it>6110 </it>in 11% of the samples. Seven of the ten IS<it>6110 </it>positive samples were positive for IS<it>1245</it>. Eleven lymph nodes from 10 pigs and 15 environmental samples were collected from the Lithuanian breeding herd and cultured for mycobacteria. <it>M. avium </it>subsp. <it>hominissuis </it>was detected in all lymph nodes and from eight samples of peat and sawdust. Isolates with identical and related IS<it>1245</it>- and IS<it>1311 </it>RFLP profiles were detected from swine and peat.</p> <p>Conclusions</p> <p>This study demonstrated cross reactions between avian and bovine tuberculin in pigs. Real-time PCR indicated infection with <it>M. avium </it>in the Serbian pigs. However, as a small proportion of the lymph nodes were positive for IS<it>6110</it>, infection with bacteria in the <it>M. tuberculosis </it>complex could not be ruled out. Analyses confirmed the presence of <it>M. avium </it>subsp. <it>hominissuis </it>in porcine and environmental samples from the Lithuanian breeding herd. The results indicate peat as a source of <it>M. avium </it>subsp. <it>hominissuis </it>infection in these pigs, and that the pigs imported to Serbia were infected with <it>M. avium </it>subsp. <it>hominissuis</it>.</p>
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