Cytotoxin and enterotoxin production as factors delineating enteropathogenicity of Aeromonas caviae

Twenty-one stool and environmental Aeromonas caviae isolates were studied for cytopathogenicity for cultured HEp-2 cells. Cytotoxic activity was demonstrated by the 21 A. caviae strains and by A. caviae ATCC 15468 after challenging HEp-2 cells with filtrates from a 24-h-old broth shake culture composed of double-strength, glucose-free Trypticase soy broth, incubated at 35°C. Heat-stable cytotoxicity was observed 5 h after the addition of 1/5 and 1/10 concentrations of filtrates and consisted of cell rounding and cell detachment. Enterotoxin activity was also demonstrated through the suckling mouse assay. These data advance the role of A. caviae as a gastrointestinal pathogen.