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REVIEWS
Molecular mechanisms of Escherichia coli pathogenicity
Matthew A. Croxen and B. Brett Finlay
Abstract | Escherichia coli is a remarkable and diverse organism. This normally harmless commensal needs only to acquire a combination of mobile genetic elements to become a highly adapted pathogen capable of causing a range of diseases, from gastroenteritis to extraintestinal infections of the urinary tract, bloodstream and central nervous system. The worldwide burden of these diseases is staggering, with hundreds of millions of people affected annually. Eight E. coli pathovars have been well characterized, and each uses a large arsenal of virulence factors to subvert host cellular functions to potentiate its virulence. In this Review, we focus on the recent advances in our understanding of the different pathogenic mechanisms that are used by various E. coli pathovars and how they cause disease in humans.
Certain isolates of http://www.ncbi.nlm.nih.gov/sites/entrez?db=genomeprj&cmd=Retrieve&dopt=Overview&list_uids=12319
Web End =Escherichia coli have been implicated in a wide range of diseases that affect either animals or humans worldwide. To date, eight pathovars and their mechanisms of disease have been extensively studied. These pathovars can be broadly classified as either diarrhoeagenic E. coli or extraintestinal E. coli (ExPEC)1. Six pathovars enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC; including Shigella), enteroaggregative E. coli (EAEC) and diffusely adherent E. coli (DAEC) are diarrhoeagenic, and two pathovars uropathogenic E. coli (UPEC) and neonatal meningitis E. coli (NMEC) are the most common ExPEC isolates (FIG. 1). Other pathovars have been identified, but their mechanisms of pathogenesis are not as well defined (BOX 1).
The pathogenic E. coli isolates share many virulence strategies. Adhesion to host cells is a requirement for all pathovars except EIEC and is frequently achieved through long appendages called fimbriae or pili. Following attachment, E. coli must subvert host cell processes, often using secreted proteins. Hijacking and manipulating host cell signalling pathways can result in the coordinated invasion of host cells, evasion of host immune responses and efficient colonization, and ultimately leads to disease (reviewed in REF. 2). Each pathovar has its own characteristic mechanisms of attaching to and exploiting host cells (see http://www.nature.com/nrmicro/journal/v8/n1/suppinfo/nrmicro2265.html
Web End =Supplementary information S1 (table)), although they often target the same host machinery. For overviews of the mechanisms...