PATHOGENICITY OF THE STRAINS OF ESCHERISCHIA COLI

Neena Nazimuddin

PATHOGENICITY OF THE STRAINS OF ESCHERISCHIA COLI


The various E. coli strains are EPEC (enteropathogenic E. coli) , ETEC (enterotoxigenic E.coli), EIEC (enteroinvasive E. coli) & EHEC (enterohemorrhagic E. coli).

EPEC are associated with infantile diarrhoea. They don't produce enterotoxins and are not invasive. These strains are called enteroadherent E. coli since they adhere to the lumen of small intestine of infants.

ETEC causes diarrhoea whose severity varies from mild to fatal (similar to cholera).Called traveller's diarrhoea and produces LT / ST or both.

EIEC are called invasive strains due to their ability to invade the intersitial epithelial cells in vivo and penetrate HeLA cells in tissue culture. Resembles shigellosis such as from mild diarrhoea to severe dysentery occurring in children and adults. The invasiveness is due to a large plasmid.

EHEC causes symptoms of diarrhoea to fatal hemorrhagic colitis leading to hemorrhagic uremic syndrome (HUS). Produces verocytotoxin which targets vascular endothelial cells. The characteristic feature therefore is renal microangiopathy. The strain O26:H1 causes hemorrhagic enteritis. It also causes pyogenic infections and septicemia.