VIRULENCE FACTORS PRODUCED BY AEROMONAS-HYDROPHILA STRAINS ISOLATED FROM DIFFERENT SOURCES

Virulence factors produced by Aeromonas hydrophila derived from water, pasteurized milk, urine and a standard strain were compared. All four strains were hemo lytic, and had protease and staphylolytic activity. Production of enterotoxin like activity in suckling mice and cytotoxin (Vero cell) were observed in A. hydrophila isolated from food, water and standard strains. Autoagglutination in broth culture was found only for two strains (standard and food strain). The biological properties of lipopolisaccharide from A. hydrophila were analysed by the mouse LD 50 determination and dermonecrotic factor. Tests of purified LPS demonstrated toxicity assayed by LD50 in mice. The characteristic lesions of local Schwartzman reaction in albino rabbits with all strains tested demonstrated the endotoxic potential of the LPS assayed. Mice challenged by the intraperitoneal route showed mortality rates of 50, 55,75 and 92%, respectively, for A. hydrophila isolated from food, water, standard and urine strains. Production of virulence factors by A. hydrophila strains isolated from food and water had a significative correlation with virulence markers found in the strains isolated from urine and standard. This finding indicates that strains of A. hydrophila isolated from food or environment sources may play a significant role as potential pathogens associated with human infections.