Production of heat-labile enterotoxin by strains of Aeromonas veronii by veronii

Three isolates of Aeromonas veronii by veronii (2 environmental, one blood infection) were examined to see if they produce any enterotoxin and, if so, to determine its characteristics. Two isolates caused fluid accumulation i n the initial rabbit ileal loop tests. The other strain did so after a sing le passage through the rabbit ileal loop. All the isolates showed gradual e nhancement of fluid secretion after each subsequent passage. Inocula of 1x1 0(4) viable cells and 0.25 mL of culture filtrate caused fluid accumulation comparable to those of toxigenic Vibrio cholerae 569B, The enterotoxic act ivity was inactivated at higher temperature, and showed biological activity over a wide range of pH, The only histopathological change observed was de pletion of mucous from goblet cells. The findings of the study indicate tha t strains of A. veronii by veronii produce a heat-labile, pH-stable diarrho eagenic factor without causing any damage to the intestinal mucosa.