Enterotoxicity of clinical and environmental isolates of Aeromonas spp.

Abstract

Of 147 isolates of three species of Aeromonas, 54 were from clinical and 93 from environmental sources. When tested for enterotoxin production, most of the isolates (56%) caused accumulation of fluid in rabbit ileal loops (RILs). Although large proportions of clinical and environmental isolates of A. caviae (55% and 65%, respectively) elicited such a response in RILs, isolates of A. hydrophila and A. sobria produced significantly more fluid (p less than 0.05). Furthermore, the environmental strains of A. hydrophila and A. sobria produced more fluid than the clinical isolates (p less than 0.05). The strains of Aeromonas spp. that caused little or no fluid accumulation in the initial experiments became enterotoxin producers after 1-3 passages through RILs, regardless of their source, and showed gradual enhancement of fluid outpouring after each passage. The present study suggests that all strains of these species of Aeromonas are potentially enterotoxigenic, whether from clinical or environmental sources.