Colibacillosis is one of the main poultry bacterial diseases, both as a primary and secondary cause. The disease has high morbidity and mortality rates, with the impact of large economic losses. Cases of colibacillosis in poultry caused by Escherichia coli have both local and systemic clinical manifestations, which can affect all parts of the organs, including the respiratory tract. The clinical symptoms include increased of chest movement, snoring, and dyspnea, depend on the severity of the disease. This study were used 40 broilers aged 14 days, which had clinical symptoms of colibacillosis and the farm had history of high collibacillosis. The aim of this study were to diagnose cases of colibacillosis by microbiology procedure, and to observe the histopathology changes of the respiratory tract (trachea, lung, and airsac).

Positive diagnose for E. coli in all samples were based on identification in Eosin Methylene Blue Agar, Triple Sugar Iron Agar, Urease, Indol, Methyl Red, Voges-Proskauer, Catalase, Citrate, Sorbitol, Glucose, Lactose, Sucrose, and Mannitol media. Pathological changes that occur in these organs are tracheitis and airsacculitis. Tracheal histopathology showed epithelial dissociation, epithelial erosion of goblet cell hyperplasia, and heterophile infiltration. There have changes in the lungs such as heterophyll infiltration, mononuclear cells in the bronchi, and emphysema. Necrosis, hemorrhage, edema, congestion, exudation of fibrinoheterophils, and fatty degeneration in airsac. Histopathology changes was confirm the case of colibacillosis. The result showed that 17 broilers (42.5%) were positive E. coli based on microbiology assessment and 5 broiler (12.5%) were showed pathological changes and histopathological changes in the respiratory tract.