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Experimental infection of white-leghorn cockerels with Macrorhabdos ornithogaster (Megabacterium)
David N Phalen1, Robert P Moore
1Texas A&M University, College of Veterinary Medicine, Department of Veterinary Pathobiology, and the Schubot Exotic Bird Health Center, College Station, TX 77843-4475, USA.
Abstract:
Macrorhabdos ornithogaster is a newly described anamorphic ascomycetous yeast that has been reported to cause a chronic, debilitating disease in many species of birds, including poultry. Study of this organism is complicated by the limited ability to grow M. ornithogaster in vitro. In this study, we showed that the chicken can be used to amplify this organism and as a model to study its pathogenicity. An infection rate of 100% was achieved in day-old chicks orally inoculated with 10(5) M. ornithogaster derived from the budgerigar (Melopsittacus undulatus). The organism was also determined to increase in number by greater than 10-fold 14 days after oral inoculation in these chicks. Chickens infected with M. ornithogaster demonstrated no sign of illness but had decreased feed conversion efficiency and consistent and characteristic histopathologic lesions in the proventriculus and isthmus of the stomach, suggesting that M. ornithogaster may represent a potential threat to the poultry industry.
Insights
Macrorhabdos ornithogaster, a yeast causing bird disease, can be studied in chickens. This model confirms 100% infection and reveals subclinical effects impacting poultry health.
Area of Science:
- Avian pathology
- Microbiology
- Veterinary science
Background:
- Macrorhabdos ornithogaster causes chronic disease in birds.
- In vitro culture of M. ornithogaster is challenging.
- Understanding M. ornithogaster pathogenicity is crucial for poultry health.
Purpose of the Study:
- To establish the chicken as an in vivo model for M. ornithogaster.
- To investigate the pathogenicity of M. ornithogaster in chickens.
- To assess the impact of M. ornithogaster on poultry.
Main Methods:
- Oral inoculation of day-old chicks with M. ornithogaster.
- Quantification of M. ornithogaster in infected chicks.
- Histopathological examination of infected chicken proventriculus and stomach.
Main Results:
- Achieved 100% infection rate in orally inoculated chicks.
- Observed over a 10-fold increase in M. ornithogaster 14 days post-inoculation.
- Identified characteristic histopathologic lesions in the proventriculus and isthmus.
Conclusions:
- Chickens serve as an effective model for amplifying and studying M. ornithogaster.
- M. ornithogaster infection leads to decreased feed conversion efficiency without overt illness.
- M. ornithogaster poses a potential threat to the poultry industry due to subclinical effects.