Chromosomal features of serotype O2:K2, an avian pathogenic .

causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic Avian pathogenic is a subgroup of extra-intestinal pathogenic and infections due to avian pathogenic have major impact on poultry production economy and welfare worldwide. An almost defining characteristic of avian pathogenic is the carriage of plasmids, which may encode virulence factors and antibiotic resistance determinates. For the same reason, plasmids of avian pathogenic have been intensively studied. However, genes encoded by the chromosome may also be important for disease manifestation and antimicrobial resistance. For the strain APEC_O2 the plasmids have been sequenced and analyzed in several studies, and APEC_O2 may therefore serve as a reference strain in future studies. Here we describe the chromosomal features of APEC_O2. APEC_O2 is a sequence type ST135, has a chromosome of 4,908,820 bp (plasmid removed), comprising 4672 protein-coding genes, 110 RNA genes, and 156 pseudogenes, with an average G + C content of 50.69%. We identified 82 insertion sequences as well as 4672 protein coding sequences, 12 predicated genomic islands, three prophage-related sequences, and two clustered regularly interspaced short palindromic repeats regions on the chromosome, suggesting the possible occurrence of horizontal gene transfer in this strain. The wildtype strain of APEC_O2 is resistant towards multiple antimicrobials, however, no (complete) antibiotic resistance genes were present on the chromosome, but a number of genes associated with extra-intestinal disease were identified. Together, the information provided here on APEC_O2 will assist in future studies of avian pathogenic strains, in particular regarding strain of APEC_O2, and aid in the general understanding of the pathogenesis of avian pathogenic .