Escherichia coli is a Gram-negative straight rod, which either uses peritrichous flagella for mobility or is nonmotile. It is a facultatively anaerobic chemoorganotroph capable of both respiratory and fermentative metabolism. E.coli serves a useful function in the body by suppressing the growth of harmful bacterial species and by synthesising appreciable amounts of vitamins. It is an important component of the biosphere. It colonizes the lower gut of animals and survives when released to the natural environment, allowing widespread dissemination to new hosts. Pathogenic E.coli strains are responsible for infection of the enteric, urinary, pulmonary and nervous systems. Comparison of 20 E.coli/Shigella strains shows the core genome to be about 2000 genes while the pan-genome has over 18,000 genes. There are multiple, striking integration hotspots that are conserved across the genomes, corresponding to regions of abundant and parallel insertions and deletions of genetic material.This strain is an avian pathogenic E.coli (APEC), and was isolated from the lung of a chicken with colisepticemia. E.coli APEC O1 is an O1:K1:H7 strain belonging to phylogroup B2 and was chosen for sequencing as it possesses traits characteristics of E.coli which cause disease outside of the intestinal tract i.e. APEC and UPEC (uropathogenic E.coli) strains. It is highly virulent in chickens. It is closely related to E.coli UTI89, a UPEC strain of E.coli (ECOUT). It contains 4 plasmids, pAPEC-O1-ColBM, pAPEC-O1-R, pAPEC-O1-Cryptic1 and pAPEC-O1-Cryptic2. Plasmid pAPEC-O1-ColBM is an F-type plasmid that produces colicins B and M and encodes a putative virulence cluster. Plasmid pAPEC-O1-R encodes resistance to eight antimicrobial agents. The cryptic plasmids are somewhat related to Yersinia-type plasmids and do not confer any apparent phenotypes. (HAMAP: ECOK1)