Regulation of Expression of Fimbriae of Human Enterotoxigenic Escherichia Coli
Adhesion of bacteria to epithelial cells of the host is the first and probably the most important step in the pathogenesis of bacterial infections. In humans, adhesion of enterotoxigenic E.coli (ETEC) to the mucosa of the small intestines is mediated by serologically distinct and host-specific fimbrial antigens on the bacterial surface. The first fimbrial antigen to be identified in human ETEC strains was colonization factor antigen I (CFA/I)1. CFA/I is a single fimbrial antigen found on ETEC producing only heat-stable (ST) enterotoxin and on ETEC producing both heat-labile and heat-stable enterotoxin (LT, ST) of at least 15 serogroups. Later CFA/11 was detected2 and was subsequently shown to consist of three distinct coli surface associated (CS) antigens, designated CS1, CS2 and CS33. Nearly all CFA/II-positive E.coli produce CS3, but those of serotype 06.H16 or 06. H- also express either CS1 or CS2 depending on their biotype: biotype A strains produce CS1 whereas those of biotypes B, C and F express CS23. Production of CS1 and CS3 has been reported in only one other ETEC strain. This strain was of serotype 0139.H28 and differs from other 0139.H28 strains that are CS3 only producers4.
KeywordsShigella Flexneri ETEC Strain Enterotoxin Production Fimbrial Subunit Compatible Plasmid
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