High frequency of K15 antigen in enterotoxigenic Escherichia coli: lack of correlation to adherence to epithelial cells or sensitivity to bactericidal effect of normal serum.

Typing of E. coli O and K antigens, testing of sensitivity to bactericidal effect of normal serum and adherence to uroepithelial as well as buccal epithelial cells was performed in enterotoxinogenic (ETEC) and normal E. coli strains. The 99 ETEC faecal strains were obtained from Swedish and Ethiopian children and adults and Swedish soldiers in Cyprus with diarrhoea. The reference faecal strains were isolated from 120 healthy Swedish children. E. coli K15 was significantly more often seen in ETEC strains than in the reference strains, always in combination with O6 antigen. K15 is hardly ever seen in nonenterotoxinogenic strains. There was no significant difference in sensitivity to bactericidal effect of serum or adherence to epithelial cells between ETEC strains and normal strains. The epidemiological significance of the findings is discussed.