ASSOCIATION BETWEEN ALPHA-HEMOLYSIN PRODUCTION AND HELA CELL-DETACHING ACTIVITY IN FECAL ISOLATES OF ESCHERICHIA-COLI

Escherichia coli isolates that cause detachment of cell monolayers dur ing in vitro adherence assays (cell-detaching E. coli [CDEC]) were rec ently reported as a potential new group of enteropathogenic bacteria. In the present study, 269 E. coli isolates from feces of children 1 to 5 years of age were identified as CDEC in a detaching assay developed with HeLa cells. The great majority of these isolates,were hemolytic, within 3 h of growth on blood agar plates and hybridized with a DNA pr obe for alpha-hemolysin (93.7%), while most of the non-detaching isola tes were hemolytic,within 24 h (3.6%) or nonhemolytic (94.8%). E. coli isolates that produced alpha hemolysin were found in 60 (30%) of 200 children with diarrhea and 47 (24%) of 200 age-matched controls. No st atistical significance was found for the differences in alpha-hemolysi n production among the matched pairs (P = 0.2). These data suggest tha t CDEC isolates are not associated with diarrhea in the population stu died.