Results of using histologic examination and acid-fast staining to confirm a diagnosis of swine mycobacteriosis made on the basis of gross examination.

Overall, 74% of the tissue specimens that meat inspectors at a large Pennsylvania packing plant identified as lesions of swine mycobacteriosis yielded Mycobacterium avium on bacteriologic culture. Histopathologic lesions compatible with mycobacteriosis were identified in 83% of the specimens; only 12% of the specimens had acid-fast staining organisms.