Isolation of nontoxigenic Vibrio cholerae O group 1 from a patient with severe gastrointestinal disease.

A nontoxigenic strain of Vibrio cholerae O group 1 was isolated in Florida from the stool of a patient with severe diarrhea. The strain had the same hemolytic and unique phage-sensitivity pattern as all toxigenic isolates from recent cases of cholera in Texas and Louisiana. Identical strains were transiently isolated from sewerage systems in two other Florida communities, suggesting that multiple human infections had occurred. This is the first indication that V. cholerae O1 strains which do not produce cholera toxin may be able to cause gastrointestinal disease in humans. The identification of these strains also raises questions about the relationship between toxigenic and nontoxigenic strains of V. cholerae O1 along the Gulf Coast of the United States.