Studies on pathogenicity of Escherichia coli isolated from chickens: Correlation between in vitro Congo-red binding properties and in vivo virulence in avian Escherichia coli

닭유래 Escherichia coli의 병원성에 관한 연구 : 시험관내 Congo-red 결합능과 병원성간의 상관관계

The correlation between in vitro Congo-red binding properties of E coli and in vivo invasiveness of the organisms in SPF chickens and mice was investigated. Congo-red positive E coli colonies were dark-red color with a typical colonial morphology of rough appearance when grown on Congo-red medium, while Congo-red negative colonies showed pale-pink color and smooth surfaced colonial morphology. Pathogenicity of 10 Congo-red positive E coli for mice was observed in 92.5% but that of 5 Congo-red negative E coli was 45%. Invasiveness of 10 Congo-red positive E coli for chickens was observed in 96% of the SPF chickens tested but that of 5 Congo-red negative E coli was 16% only. These results of pathogenicity studies with E coli isolates indicate a significant correlation between Congo-red binding ability and virulence in avian Escherichia coli.