Lethal doses of 11 clinical and environmental isolates of Vibrio vulnificus were determined in suckling mice after oral challenge. With one exception, isolates that were virulent to iron-overloaded adult mice after intraperitoneal inoculation were highly lethal to the infant mice (>50% lethality at 105 CFU/mouse). The virulent isolate that failed to kill infant mice at 105 CFU had lost its invasiveness. Conditionally virulent isolates that were virulent only to simultaneously iron-overloaded and immunosuppressed adult mice required > 109 CFU to kill the infant mice. Avirulent isolates failed to kill at >109 CFU/mouse. There were no significant differences in the lethalities of clinical and environmental isolates. These findings demonstrated a close correlation between virulence in the iron-overloaded adult mouse and infectivity by the oral route.

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Author notes

1Present address: U.S. Environmental Protection Agency, E.M.S.L., 26 West St. Clair, Cincinnati, OH 45268.

2Present address: U.S. Environmental Protection Agency, H.E.R.L., 26 West St. Clair, Cincinnati, OH 45268.