Association of Aeromonas sobria with human infection

Abstract

Fifteen Aeromonas isolates from various human infections and 9 isolates from polluted water were identified as A. hydrophila or A. sobria and examined for cytotoxigenicity, enterotoxigenicity, adherence to epithelial cells and other virulence-associated factors, including proteases, lipases, elastases and hemolysins. Two groups of organisms (1 and 2) were distinguishable based on differences in LD50 in mice and cytotoxicity for (mouse) Y-1 adrenal cells. Group 1 clinical and environmental strains had LD50 of < 107 colony-forming units (CFU), were cytotoxic, frequently possessed several virulence-associated factors and had lysine decarboxylase-positive or Voges-Proskauer-positive phenotypes or both. Piliation of Aeromonas was associated strongly with ability to adhere to human buccal cells and these characteristics were associated with group 1 strains. Group 2 clinical and environmental strains had LD50 of .gtoreq. 107 CFU, were not cytotoxic and usually were lysine decarboxylase negative or Voges-Proskauer negative or both. Clinical strains in group 2 exhibited enterotoxigenicity, which was not detected in group 2 environmental strains. A. sobria was more frequently associated with human infections; 13 of the 15 clinical strains were A. sobria and 2 were A. hydrophila. The majority of the environmental strains (7 of 9) were A. hydrophila.