Comparison of lethalities in mouse versus goldfish for clinical and food isolates ofAeromonas hydrophila

The lethality of 16 clinical or food isolates ofAeromonas hydrophila was assessed by determination of LD50 (i.p.) in mice and goldfish. In mice LD50 values for the variousA. hydrophila strains were similar, ranging from 1.2–21.0×108 cells/animal. A wider range of LD50 values, 0.03–11.8×108 cells/animal, was observed with goldfish. Lethality was not correlated between the two test animals. Further, cytotoxic response in Y-1 adrenal cells did not correlate with lethality in either test animal. It appears that lethality is not a good measure of potential enterotoxigenicity, but may be useful in assessing the invasive character of isolates causing systemic infections in immunocompromised hosts.