Two Clinical Isolates of Mycoplasma hyosynoviae Show Differing Pattern of Lameness and Pathogen Detection in Experimentally Challenged Pigs

June 15, 2016 — 

Mycoplasma hyosynoviae is known to colonize and cause disease in growing-finishing pigs. While M. hyosynoviae-associated arthritis has previously been experimentally induced, this study compared two clinical isolates separately by inoculating cesarean-derived colostrum-deprived and specific-pathogen-free pigs growing pigs. After intranasal or intravenous inoculation, the proportion and distribution pattern of clinical cases was compared, in addition to the severity of lameness. Tonsils were found to be the primary site of colonization, while bacteremia was rarely detected prior to the observation of clinical signs. Regardless of the clinical isolate, route of inoculation, or volume of inocula, histopathological alterations and tissue invasion were detected in multiple joints, indicating an apparent lack of specific joint tropism. Acute disease was seen primarily 7-10 days post-inoculation. The variability in the severity of synovial microscopic lesions and in the pathogen detection in joint cavities suggests that the duration of joint infection may influence the diagnostic accuracy. In summary, these findings demonstrate that diagnosis of M. hyosynoviae-associated arthritis can be influenced by the clinical isolate, and provides a study platform to investigate the colonization and virulence potential of field isolates. That approach can be particularly relevant to auxiliate in surveillance and testing of therapeutic and/or vaccine candidates.
Neto JC, Raymond M, Bower L, Ramirez A, Madson DM, Rosey EL, Rapp-Gabrielson VJ, Strait EL; Two Clinical Isolates of Mycoplasma Hyosynoviae Show Differing Pattern of Lameness and Pathogen Detection in Experimentally Challenged Pigs; J Vet Sci. 2016 Jun 13. [Epub ahead of print] PMID: 27297416