Molecular subtyping of Vibrio cholerae O1 strains recently isolated from patient, food and environmental samples in Spain.

Nineteen Vibrio cholerae O1 strains isolated in Spain from patient, food and environmental samples in the period 1990-1992 were characterized by detection of cholera toxin by enzyme immunoassay, detection of cholera toxin gene by polymerase chain reaction, and by biotyping, ribotyping and pulsed-field gel electrophoresis. Ten isolates were toxigenic and were further characterized by multilocus enzyme electrophoresis. Molecular subtyping methods allowed precise differentiation between isolates, indicating their geographic origin. Isolates associated with the ongoing seventh pandemic were distinguishable from those associated with the present Latin American epidemic. All isolates from the environment and seafood were nontoxigenic, and were genetically different and more diverse than toxigenic isolates. The data suggest that a focus of endemic cholera does not exist in Spain, and that the analyzed nontoxigenic Vibrio cholerae O1 isolates from imported seafood were not a threat to public health.