Studies on the Enteropathogenic Mechanism of Non-O 1Vibrio choleraeIsolated from the Environment and Fish in Toyama Prefecture

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Abstract
Enteropathogenic mechanisms of non-O 1 V. cholerae were investigated using strains from the environment and those from fish in Toyama Prefecture. None of the 93 non-O 1 V. cholerae strains produced a detectable level of cholera toxin-like enterotoxin (CT-like enterotoxin) in Syncase medium; 23 strains showed a distinct fluid accumulation in the rabbit ileal loop test (RIL). These RIL-positive strains neither produced CT-like-enterotoxin in vitro in the other 4 kinds of media which are considered suitable for CT production, nor in vivo in the RIL. Of RIL-positive strains, .apprx. 1/3 produced a fluid accumulating factor (FAF) which was not neutralized with anti-CT serum. FAF of a representative strain (Strain 79-9-2) was inactivated by heating at 100.degree. C for 10 min and had a MW of 50,000-100,000 daltons. Most accumulated fluids in RIL after inoculation with whole cultures of RIL-positive strains contained hemolytic and cytotoxic principles. Desquamation of epithelial cells, inflammatory edema, neutrophil infiltration, loss of goblet cells and frequent hemorrhages were observed in sections of ligated ileal loop inoculated with whole cultures or concentrated culture filtrates of CT-like-enterotoxin-negative but RIL-positive strains. Neither desquamation of epithelial cells nor hemorrhage was observed in sections after inoculation with those of a CT-like-enterotoxin positive strain (Strain E 8498). Thus, most RIL-positive non-O 1 V. cholerae strains from the environment and fish isolated in Toyama Prefecture produce little CT-like-enterotoxin, but some of them produce FAF with cytotoxic activities.