Escherichia coli in fecal flora of healthy adults: serotypes, P and type 1C fimbriae, non-P mannose-resistant adhesins, and hemolytic activity.

Escherichia coli strains from feces of 287 healthy adults were analyzed for O:K serotypes, P and type 1C fimbriae, non-P mannose-resistant adhesins, and hemolysin production. O1, O2, O6, O7, O18, O25, and rough-type lipopolysaccharide accounted for 40% of all isolates. K antigen was present in 62%; K1 was identified in 30% and K5 in 10%. O1, O2, O18, rough lipopolysaccharide, and P fimbriation were significantly associated with K1 and O6, O25, and type 1C fimbriation with K5. The overall prevalence of virulence-associated determinants was 22%; 7% of the strains possessed two or three of them. These determinants were most often associated with 9 serotypes (O1:K1, O2:K1, O6:K1, O6:K5, O7:K1, O16:K1, O22:K-, O25:K5, and R:K1) among which their prevalence was 43%, three times greater than among the remaining strains (P < .001). No enteropathogenic or enterohemorrhagic E. coli-associated serotypes were detected.