Pathological and microbiological investigations into cases of bacterial chondronecrosis and osteomyelitis in broiler poultry

Abstract

Bacterial chondronecrosis and osteomyelitis (BCO) is increasingly recognized as a major cause of lameness in commercial broilers chickens worldwide, but the pathogenesis of the condition is incompletely understood. This was a longitudinal study of 20 commercial broiler farms in Victoria, Australia, to investigate the aetiology and pathology of BCO. Thorough postmortem examination was performed on culled and dead birds (n = 325) from 20 different flocks at either 1 week, 4 weeks or 5 weeks of age and samples were analysed by conventional bacteriology, molecular identification of infectious organisms detected, serology and histopathology. BCO occurs throughout the life of broiler flocks at a very high rate, with lesions detected in 28% (95% CI 23-34%) of the mortalities and culls. The condition occurs with similar prevalence in both the femur and tibiotarsus. BCO is an infectious process that appears to result from bacteraemia and haematological spread of bacterial pathogens, especially Escherichia coli, to the bones, with 65.3% bacterial isolates from histologically confirmed BCO identified as E. coli, 11.5% as Staphylococcus and the remainder composed of mixed infections or a range of other minor isolates. We observed that almost all E. coli isolated from cases of BCO are avian pathogenic E. coli, suggesting that preventative measures should be directed at this organism.

Loop-mediated isothermal amplification assay forEnterococcus sp., E. coliandS. aureusin chicken

“…Enterococci, including E. faecalis, E. faecium, E. avium, E. durans , and E. gallinarum , are frequently isolated from the litter, feed, dead-shell, or 1-day-old chicks in poultry farms (2, 4). In one study, avian pathogenic E. coli was recovered from over 90% of bacteriologically tested chickens with lameness (5), and was the most frequently isolated bacterium from chickens with BCO (30). S. aureus is the major pathogen responsible for bone and joint infections (16), and is also isolated from the litter, feeders, drinkers, and the air in poultry houses (17, 24, 26).…”

“…An investigation in Bulgaria revealed the significant scale of the problem, with lameness accounting for 10% of mortality in lame chickens, and BCO accounting for more than 90% of these cases (5). Although the complex pathogenicity mechanism of BCO is not entirely understood, Enterococcus sp ., avian pathogenic Escherichia coli , and Staphylococcus aureus are recognized important pathogens associated with BCO (5, 7, 17, 23, 29–30). These bacteria are ubiquitous in poultry environments where the birds are hatched, reared, or processed; they are transmitted to chicks from breeder parents, contaminated eggs, or hatchery sources by opportunistic infection (18, 29).…”

Origin of broiler carcass condemnations

“…Litter moisture, which causes ulcerative dermatitis and feet lesions, can affect other body parts in direct contact with the litter, such as the breast. The high content of contaminants can also cause cellulitis (Part et al, 2016), which is associated with serositis, airsaccullitis, pericarditis, perihepatitis, peritonitis, and salpingitis (Kasuya et al, 2017) and constitutes one of the main causes of condemnation in slaughterhouses, with implications for public health due to its principal etiologic agent, Escherichia coli Wijesurendra et al, 2017).…”

Genetic selection of broilers and welfare consequences: a review

“…Bacterial chondronecrosis with osteomyelitis (BCO) is a condition triggered by a bacterial infection of the bone that often results in necrosis and bone fracture (Wijesurendra et al 2017). It has been reported to be the most common cause of severe leg disorders in modern broilers (Bradshaw, Kirkden, and Broom 2002).…”

“…It has been reported to be the most common cause of severe leg disorders in modern broilers (Bradshaw, Kirkden, and Broom 2002). A recent Australian study involving 20 commercial broiler farms found BCO lesions in 28% of necropsied birds (culls and mortalities) (Wijesurendra et al 2017).…”