One hundred and fifty samples from hatched chicks were collected from different hatcheries at Assiut governorate, they had abnormalities, deformity, lameness and could not stand on their legs. Yersinia pseudotuberculosis was isolated at rate of 36.6 % while Yersinia enterocolitica was isolated at rate of 3 %. Experimental infection of 3 days old healthy chicks subcutaneous by Yersinia pseudotuberculosis isolate revealed death of all chicks within 2 days and septicemia. While oral route of infection revealed depression of the chicks, enlargement and congestion of liver and spleen with necrosis, enlargement of kidneys with precipitation of uric acid in the ureteres and some cases in the 27 th day postinfection had lamness and could not stand. Also paralysis of legs was appeared before death which its rate reached to 5 %. Inoculation of fertile chicken eggs (5 - 7 days) intra yolk sac with the isolated organism revealed deaths of all embryos within 3 days postinfection, while inoculation of fertile chicken eggs (11 days) through chorio allantoic membrane showing death of all embryos within 6 – 8 days postinoculation with congestion and stunting of the embryos, on the other hand swabbing of the outershell of fertile chicken eggs with the isolated organism leads to hatching of abnormal chicks with the same symptoms of the naturally infected chicks. Reisolation of Yersinia from experimentally infected chicks was succeded. Sensitivity test revealed that gentamycin, rifampicin and chloramphenicol were the most effective drugs in vitro.
The aim of this work is designed to cover the following points:-
- Isolation and Identification of Yersinia organism and its incidence in the newly hatched chicks.
- Experimental infection of the isolated organism to 3 – days old chicks and inoculation of embryonated chicken eggs through different routes with the isolated organism.
- In vitro sensitivity test to the isolated organism to different antimicrobial discs to show the most effective drugs.