Oral Infectivity of Vibrio vulnificus in Suckling Mice

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.