Molecular and Serological Characteristics of Avian Pathogenic Isolated from Various Clinical Cases of Poultry Colibacillosis in Poland.

infections are a major problem in modern poultry production. Avian pathogenic (APEC) strains have several mechanisms that enable them to colonize various ecosystems. In this study, 290 isolates were recovered from clinical cases of colibacillosis in chicken and turkey broilers and from laying and breeding hens. The samples were taken from organs with pathological changes suggesting colibacillosis. The lesions were assigned to three groups depending on their advancement, of which the largest (60% of the isolates) was group 3, with the most extensive changes. The most common serotype was shown to be O78 (14%). The most frequently detected gene among those tested was , while was the least prevalent. An analysis of the number of genes present per isolate revealed that the presence of four genes was the most common (22%), while only 1% of the strains tested had all eight genes. The most frequently detected genes for each serotype were and for O78; and for O1; , , and for O2, and and for O8, for which the least frequent was . All O18 serotype strains had the gene, while none had the gene.