Actinobacillus pleuropneumoniae osteomyelitis in pigs demonstrated by fluorescent in situ hybridization

Necrotizing osteomyelitis and fibrinopurulent arthritis with isolation of A ctinobacillus pleuropneumoniae serotype 2 is reported in two pigs from a he rd with lameness and mild coughing problems among 8 to 12-week-old pigs. Ap plication of fluorescent in situ hybridization targeting 16S ribosomal RNA of A. pleuropneumoniae in formalin-fixed tissue was performed to verify the association of A. pleuropneumoniae with the bone and joint lesions. By in situ hybridization A. pleuropneumoniae was demonstrated as multiple microco lonies or single cells dispersed in focal fibrinonecrotizing pleuropneumoni a, in joints with arthritis, and in bone necroses including lysis of growth plate and suppurative inflammation in the adjacent trabecular metaphysis, thus demonstrating that well-known infections manifest new, unusual lesions .