RESUMEN
Pasteurella multocida [P. multocida] and several bacterial agents associated with some problems in ducks were investigated in different governmental and private farms at Assiut Governorate. Samples were taken from different tissues showing pathological evidence of infection such as liver, heart, trachea, lungs and spleen as well as from blood. All samples were subjected for bacterial, mycoplasma and viral isolation. It was found that the total percentages of isolated bacteria were [51.7%], P. multocida [25%], E. coli [16.87%], Campylobacter jejuni [3.3%], and mixed infection with P. multocida and E. coli [6.7%]. On the other hand, all examined samples were negative for mycoplasma and viruses. Moreover, experimental infection was carried out with isolated P. multocida in two weeks old ducks. After 72 h of infection, samples were taken for both bacterial isolation and histopathological examination. P. multocida was also isolated from experimentally infected ducks. When they subjected to the in vitro sensitivity tests, it was shown that they were highly sensitive to gentamycin, norfloxacin and oxytetracyclin. Among examined tissues of experimentally-infected ducks, liver, heart, brains and lungs showed multiple pathological changes. Thus, the present study has shown the role of P. multocida as a causative agent of some problems in duck farms at Assiut Governorate and their sensitivity for some antibiotics