Management of Bacterial Chondronecrosis with Osteomyelitis: Impact of Non- Pathogenic and Pathogenic Bacterial Isolates on Lameness in Birds

Lameness in poultry negatively impacts the quality and cost of poultry production with annual losses of millions of dollars. In broiler chickens, bacterial chondronecrosis with osteomyelitis (BCO) is a common cause of lameness. We have used a wire flooring model to induce lameness, and identified Staphylococcus agnetis (commonly associated with mastitis in cows) as a causative agent of BCO. Administration of a chicken S. agnetis isolate in drinking water at 20 days of age can induce high incidence of BCO in birds on wire flooring. Our hypothesis is that rearing chicks on wire flooring leads to stress-induced bacterial translocation across the intestinal epithelium into the blood. Eventually, S. agnetis and other pathogenic species appear to colonize the predisposed proximal femoral and tibial growth plates inducing necrosis and lameness by 40-56 days. Recently, we have identified Staphylococcus hyicus (another species associated with mastitis) from BCO infections. We have been analyzing the genomes of S. agnetis and S. hyicus to attempt to dissect the genomic determinants for pathogenesis in BCO. Defining the likely route of transmission to broilers, and genomic analyses will contribute substantially to the development of measures for mitigating BCO losses in poultry. We are investigating the pathogenesis and phylogenomic relationships between our poultry isolates and isolates obtained from commercial broiler operations. We’ve been working to identify which species are more virulent, and whether non-pathogenic related species could protect against lameness. Additionally, we have tested prebiotics and probiotics for reducing lameness. This work has revealed that the spread of the bacterium within a flock may be through either the gastrointestinal tract or through the pulmonary epithelia. Our ultimate goal is to develop methods for management to reduce pathogen colonization and transmission.

Broiler; lameness; bacteria; pathogen; genome; leg