Biotyping and virulence factors in clinical and environmental isolates of Aeromonas species.

Biochemical characteristics and virulence factors were compared in 147 Aeromonas spp. isolated from patients with diarrhea and in 94 strains isolated from metropolitan water supplies in the same area during the same period. Fermentation of arabinose occurred with 58.5% of the environmental strains and 15% of the clinical isolates; 39.4% of the strains from water and 6.8% of the fecal isolates fermented salicin. The frequency of esculin hydrolysis was the same in both groups. Ninety-one percent of clinical isolates and 70.2% of environmental strains were enterotoxigenic and, except for four clinical isolates, all of these strains also produced hemolysins. Hemagglutination that was inhibited by fucose and mannose but not by galactose was found in 67% of the water isolates and 10.2% of the clinical strains. Although the distribution of several characteristics differs in clinical and environmental strains, many of the strains found in water have properties identical with those of the clinical isolates. We suggest that such strains may be potential enteric pathogens.