What are the diarrheagenic subtypes of E coli?
There are six subtypes of diarrheagenic E. coli:
- • Enterotoxigenic E. coli (ETEC) —notable for toxin production, either heat labile, heat stable, or both, and is the most common cause of travelers’ diarrhea in many developing countries.
- • Diffusely adherent E. coli and enteropathogenic E. coli —common in children of younger than 2 years. Tight adherence to small bowel.
- • Enteroinvasive E. coli (EIEC) —able to invade mucosal lining (type 3 secretory apparatus); causes a presentation similar to Shigella enterocolitis.
- • Enteroadherent/aggregative E. coli (EAEC) —associated cause of persistent chronic diarrhea in children and travelers. A common cause of traveler’s diarrhea in addition to ETEC.
- • EHEC —associated colitis and bloody diarrhea, and the hemolytic uremic syndrome (HUS). Pathologic findings are secondary to Shigalike toxin production. Serotype O157:H7 is the most common EHEC representative. It is most commonly transmitted through food supply, in particular contaminated beef products. It is isolated on Sorbitol-MacConkey agar and toxin production with enzyme-linked immunosorbent assay (does not ferment sorbitol). HUS occurs in approximately 5% to 15% of pediatric cases in which antibiotic therapy has been associated with the onset of HUS.
- • STEC —Shiga toxin–producing strains other than EHEC. A recent outbreak of O104:H4 in 2011 resulted in illness in primarily adults and was associated with HUS in some cases.