AEROMONAS-HYDROPHILA ISOLATED FROM FOOD AND DRINKING-WATER - HEMAGGLUTINATION, HEMOLYSIS, AND CYTOTOXICITY FOR A HUMAN INTESTINAL-CELL LINE(HT-29)

Aeromonas hydrophila isolated from food and drinking water was tested for pathogenicity by studying its hemolysis, hemagglutination, and cyt otoxicity. Hemolysis, tested on erythrocytes from six different specie s, was more frequently seen with water isolates (64%) than with food i solates (48%), Hemagglutination was more frequently encountered with f ood isolates (92%) than with water isolates (73%). Cytotoxicity, evalu ated on seven cell lines, was frequently observed with food isolates ( 92%) and with water isolates (73%). Heat treatment (56 degrees C for 1 0 min) of culture supernatant fluids inhibited the toxicity of some bu t not all toxin-producing isolates. Our results suggest that the human intestinal cell line HT-29 could be a useful complement for testing A . hydrophila exotoxins and for studying the enteropathogenicity of thi s species for humans.