Pathogenic Escherichia coli

Abstract

In addition to being an important member of the normal intestinal microflora of humans and other mammals, the species Escherichia coli contains many pathotypes that cause a variety of diseases. At least six different pathotypes cause enteric disease, such as diarrhoea or dysentery, and other pathotypes cause extra-intestinal infections, including urinary tract infections and meningitis. Virulence factors of E. coli can affect a wide range of eukaryotic cellular processes, including cell signalling, ion secretion, protein synthesis, mitosis, cytoskeletal function and mitochondrial function. Virulence factors of pathogenic E. coli are frequently encoded on genetic elements such as plasmids, bacteriophage, transposons and pathogenicity islands that can be mobilized into different strains to create novel combinations of virulence factors. The genomic structure of the E. coli pathotypes that have been sequenced so far show a striking mosaic pattern, with 2,000 genes present in 247 islands in one pathotype that are not present in K-12. Up to 0.53 MB of DNA present in K-12 can also be absent from pathogenic E. coli. Genes that encode virulence factors of pathogenic E. coli are regulated by both pathotype-specific regulators that are absent from commensal E. coli, and by 'housekeeping' regulators that are present in commensal E. coli.