Enterotoxicity, haemolytic activity and antibiotic susceptibility of Aeromonas eucrenophila strains isolated from water and infected fish.

Strains of A. eucrenophila isolated from fresh water (2 strains) and infected fish (4 strains) were tested for haemolytic activity and enterotoxicity and any correlation between them. Also, the resistance patterns of A. eucrenophila were tested especially in relation to ampicillin. None of the A. eucrenophila strains caused fluid accumulation in the initial tests, however, they did so only after one to four sequential passages through the gut of a susceptible host. All the strains of A. eucrenophila showed beta-haemolytic activities. Production of beta-haemolysin could be correlated with enterotoxicity. Since all the strains of A. eucrenophila were resistant to ampicillin, media containing this antibiotic may be used for their isolation from diverse sources.