Rapid identification of tissue micro-organisms in skin biopsy specimens from domestic animals using polyclonal BCG antibody

Immunostaining with polyclonal anti-Mycobacterium bovis (BCG) was evaluated as a single screening method for the histological identification of micro- organisms in skin biopsy specimens from various veterinary species. Confirm ed archival cases infected with Mycobacteria, Nocardia, Actinobacillus, Act inomyces, Streptococcus/Staphylococcus, Dermatophilus, spirochetes, Blastom yces, Coccidioides, Cryptococcus. Histoplasma, dermatophytes, Malassezia, S porothrix, Leishmania, Pythium, phaeohyphomycetes and Prorotheca organisms were selected. A total of 70 skin biopsy specimens from the dog, cat, horse . ox and llama were evaluated. The anti-BCG immunostain labelled bacteria a nd fungi with high sensitivity and minimal background staining but did not label spirochetes and protozoa (Leishmania). Differences were not noted bet ween veterinary species. The results indicate that immunostaining with poly clonal anti-BCG is a suitable screening technique for the rapid identificat ion of most common bacterial and fungal organisms in paraffin-embedded spec imens. Also, mycobacterial and nocardial organisms were identified more rea dily with the anti-BCG immunostain in comparison to the histochemical stain s.