Pathogenicity of Aeromonas sp. for BALB/c mice.

Clinical strains of Aeromonas hvdrophlla and Aeromonas sobria were used to develop a mouse model for determining virulence potentials of food isolates. lntraperitoneal injection with these strains caused hemorrhaging and death of 10—12 week old male BALB/c mice within 24 h post challenge. Nonsupplemented injections of Aeromonas sp. suspensions resulted in a median LD 50 value of 4.9 X 10 cells, whereas supplementation with 0.1 ml of 5% iron dextran with the bacterium decreased the LD 50 value to 3.1 X 10 cells. Immunosuppression of the mice with cadmium chloride did not substantially alter the lethality for mice. Boiled suspensions 109 cells did not cause more deaths, indicating a lack of pathological contribution by the LPS component when using this approach for virulence assessment. lsolates of Aeromonas sp. from retail chicken, beef and pork products were supplemented with iron dextrart and injected into BALB/c male mice. Twenty-two of 26 mice injected with 26 A. hydrophila food isolates died; 13 of 14 mice injected with A. sobria isolates died; and 10 of 16 mice injected with A. cav!ae isolates died. These results indicate that approximately 80% of foodborne aeromonas are lethal for mice via intraperitoneal challenge. This virulence assay may or may not be an appropriate choice to assess the potentials of foodborne isolates of Aeromonas sp. to cause disease in humans (JPMA 38: 47 1988).