Study of the pathological importance of Escherichia coli in respiratory infection of broiler chickens

This study showed airsacculitis when 12 days broilers inoculated in the left thoracic air sacs with 0.1 ml suspension of type-1 E.coli that contained (1 x 10 8 ) cfu/ml and noticed after72 hours. The first clinical signs occur after 3 hours of inoculation as acute respiratory signs including dyspnea and respiratory rales. The pathological changes appear as sever air sacculitis with thin layer of fibrenous surrounding the heart after 24 hours of inoculation, then became more thick layer of fibrenous surrounding the heart, airsac and lungs, and spots of necrosis in the liver after 72 hours of inoculation. The first mortality of chicks occurs after 12 hours of inoculation. In concerted with bacterial count, blood and liver showed highest number of E.coli after 24 hours of inoculation and after 12 hours of inoculation in both lungs and airsacs.