Development of an experimental model of bacterial chondronecrosis with osteomyelitis in broilers following exposure to Staphylococcus aureus by aerosol, and inoculation with chicken anaemia and infectious bursal disease viruses

Abstract

A series of experiments was designed in an attempt to reproduce bacterial chondronecrosis with osteomyelitis in broiler chickens using a natural route of infection. Birds in isolators were exposed to a suspension of Staphylococcus aureus by aerosol or exposed to S. aureus and subsequently inoculated with chicken anaemia virus (CAV) alone, or with CAV and infectious bursal disease virus (IBDV). Subsequently, S. aureus was recovered and bacterial chondronecrosis with osteomyelitis was diagnosed, by histology, in the proximal end of the femur and/or tibiotarsus of lame birds exposed to S. aureus with and without CAV and IBDV infections. Birds fed 60% of the recommended feed intake for the breed developed a lower incidence of S. aureus infection and/or bacterial chondronecrosis (P < 0.05) than birds fed 100% of the recommended intake. A significantly lower incidence of S. aureus was recovered (P < 0.05) in birds simultaneously exposed to S. aureus and inoculated with CAV and IBDV at day 21, than in birds exposed to S. aureus at day 10, and inoculated with CAV and IBDV at day 21. With the exception of birds exposed to S. aureus at 1 day old, a higher incidence of bacterial chondronecrosis was diagnosed in birds exposed to S. aureus and inoculated with CAV and IBDV than in birds exposed to S. aureus alone. It is hypothesised that inoculation with CAV and IBDV at day 21 enhanced the development of bacterial chondronecrosis in birds exposed to S. aureus at day 10 and fed 100% of the recommended feed intake or ad libitum.

Bacterial Osteomyelitis in a 3-Week-Old Broiler Chicken Associated WithEnterococcus hirae

“…No such macroscopic lesions were seen by sagittal sawing of the femoral bones. However, macroscopic lesions may be present in only 40% to 67% of cases, 7,11 and many osteomyelitic lesions are detectable only by histologic examination, 15 as in this case. The histologic findings in the proximal femur correspond to findings in staphylococcal and E coli osteomyelitis; however, chondronecrosis was not seen.…”

“…However, no histologic description of bone was mentioned. This case illustrates that the absence of macroscopic bone lesions in lame chickens should encourage histopathologic and bacteriologic examination of the proximal part of both femur and tibiotarsus to confirm a diagnosis and prevent underdiagnosis, as described by Emslie et al 7 and McNamee et al 11 Osteomyelitis was histologically identified in the proximal femur of a lame chicken, and detection of gram-positive coccoid bacteria-as consistent with Enterococcus spp within the bone lesions and the pure culture of E hirae from the boneare reported for the first time, suggesting that E hirae was the cause of the osteomyelitic lesions.…”

The anti-nuclease humoral immune response of broiler chickens exposed toStaphylococcus aureus, infectious bursal disease virus and chicken anaemia virus in an experimental model for bacterial chondronecrosis and osteomyelitis

“…Pulsed field gel electrophoresis has characterized this strain as the predominant type recovered from broilers with clinical disease in Northern Ireland . The CAV and IBDV strains used were CUX1 and G9, respectively (McNamee et al ., 1999).…”

“…aureus and virus strains. A S. aureus strain recovered from a naturally occurring case of BCO, designated Isolate 24, was used (McNamee et al ., 1999). Pulsed field gel electrophoresis has characterized this strain as the predominant type recovered from broilers with clinical disease in Northern Ireland .…”

“…In this study, a commercially purified preparation of the S. aureus protein nuclease was tested for suitability as an antigen to detect antibody associated with S. aureus in sera from chickens that had been exposed to aerosolized S. aureus during experiments concerning the model for BCO in broiler chickens (McNamee et al ., 1999). The influence of the age of the bird, S. aureus infection status and the CAV and IBDV infection status on the levels of S. aureus antibody present was also determined.…”