Acute Feedlot Arthritis Associated with Distinct Strains of Mycoplasma bovis
DOI:
https://doi.org/10.21423/aabppro19946281Keywords:
arthritis, acute feedlot outbreaks, M. bovis, strains, antimicrobial therapy, mycoplasma strainsAbstract
Acute feedlot arthritis outbreaks have been reported recently
throughout the Midwestern US. A common feature of these outbreaks has been poor responsiveness to antimicrobial therapy and the isolation of Mycoplasma bovis from joint fluid specimens. Morbidity and mortality of these outbreaks reached significant levels, and prompted an investigation of the mycoplasma strains recovered. Four strains of M. bovis recovered from acute arthritis cases were compared with 5 strains of M. bovis recovered from enzootic pneumonia cases. Invasive ability of these strains was compared in vitro using tracheal mucosa explants, and 1 strain of each type was inoculated intratracheally in calves. Arthritis-associated strains were more invasive in vitro. One arthritis-associated strain did not produce mycoplasmemia in 4 infected calves, but was recovered from nasal mucosa. In contrast, a respiratory strain of M. bovis gave reproducible mycoplasmemia but was not recovered from nasal mucosa. Phenotypic differences among strains of M. bovis warrant further study of the pathogenic and immunogenic properties of strains of M. bovis.