Bacteremia in suckling rabbits after oral challenge with Vibrio parahaemolyticus

Abstract

Vibrio parahaemolyticus, a halophilic marine enteropathogen, produces diarrhea in man after ingestion of contaminated seafood. Only strains capable of producing beta-hemolysis (Kanagawa-positive strains) are enteropathogenic. Yet the majority of marine isolants are nonhemolytic and Kanagawa negative. Studies were initiated in suckling rabbits in an attempt to elucidate pathogenetic mechanisms. Fasting animals were infected orally with Kanagawa-positive and Kanagawa-negative strains of V. parahaemolyticus, V. cholerae, two enteropathogenic strains of Escherichia coli, Shigella flexneri, and strains of salmonellae. Seven hours postchallenge, cardiac blood, liver, and spleen cultures were obtained. V. parahaemolyticus strains failed to induce intestinal fluid accumulation during this study period. Bacteremia occurred in animals challenged with Kanagawa-positive V. parahaemolyticus, S. flexneri, and salmonella strains only. Animal passage increased the ability of V. parahaemolyticus to cause bacteremia. Liver and spleen cultures were positive in approximately 50% of animals challenged with the Kanagawa-positive strains of V. parphaemolyticus. The ability of this organism to penetrate the intestinal epithelium of suckling rabbits may represent a specific property that plays a role in pathogenesis.