Avian pathogenic Escherichia coli: diagnosis, virulence and prevention.

Avian pathogenic Escherichia coli (APEC) causes colibacillosis within poultry flocks all around the world. There is a number of virulence mechanisms involved in the disease process in poultry and determination of some of the responsible genes is important for diagnosis of colibacillosis. In this work, research data regarding diagnostics of APEC and how certain clonal lineages could cause infection in different hosts is presented. In order to determine virulence genotype of APEC, multiplex polymerase chain reaction, based on a published sequence of seven pairs of primers (iroN, ompT, hlyF, iss, iutA, elitC and cvaC), was used in our laboratory. It was established in the research of other scientists that isolates with two or more of these genes can develop pathogenic phenotype, while isolates with one or none of the genes are mostly commensal E. coli. Additionally, virulence mechanisms in APEC were also briefly described. It was emphasized that resistance genes and virulence genes are sometimes co-located on the same plasmid and that such plasmids could be shared among related or unrelated bacteria species. Since APEC often confers resistance to antibiotics, the therapy is less effective in poultry with multidrug resistant strains. It was concluded that good management practice, treatment with probiotics and/or vaccination are necessary to reduce colibacillosis outbreaks. This approach is even more pronounced since APEC resides in intestine of healthy poultry and could cause disease if poultry is exposed to various stressors.