[Aeromonas spp. isolated from human feces. Species and pathogenicity factors]

The role of Aeromonas genus as a primary intestinal pathogen is still a matter of controversy. We have studied the isolation of Aeromonas spp. from human stools samples, looking for the production of pathogenic factors and its relationship with different species. From a total of 471 strains isolated, 241 were A. caviae, 127 A. sobria, 89 A. hydrophila and 14 non-typable strains. The pathogenic factors production was studied in a bacteria-free filtrate from a 18 hours trypticase-soy broth culture. Enterotoxin production was assessed by suckling-mice test, cytotoxin production by using Hela cells monolayer and hemolysin production by double dilution from the filtrate, plated in microdilution plates, against rabbit red-blood cells. Enterotoxin production test was positive for A. sobria, A. hydrophila and A. caviae in 81.1%, 62.9% and 7.0% of strains respectively. Cytotoxin production was also positive for these species in 96.6%, 76.4% and 4.1%, and hemolysin production was positive in 95.3%, 70.7% and 2.4% of the strains respectively.