EPIDEMIOLOGIC APPLICATION OF A STANDARDIZED RIBOTYPE SCHEME FOR VIBRIO-CHOLERAE 01

A standardized scheme of 27 different BglI ribotypes and subtypes of V ibrio cholerae O1 strains is proposed on the basis of data from 214 hu man and environmental strains isolated in 35 countries and 14 U.S. sta tes over the past 60 years. The ribotype patterns obtained are reprodu cible and stable over time. Seven different but very similar ribotypes (1a to 1g) were observed among 16 strains of the classical biotype. T wenty ribotypes and subtypes were identified among 198 V. cholerae 01 strains of the El Tor biotype. Six different patterns were found among the strains causing the current seventh pandemic. Strains of ribotype 8 originated only in central African countries, while those of riboty pe 3 originated mainly in Asia and the Pacific Islands. The most widel y distributed strains were those of ribotype 6, which was subdivided i nto three very similar but still distinguishable subtypes. The present Latin American epidemic is caused by strains of ribotype 5. Strains o f this ribotype were isolated from several other geographic locations but can be differentiated from the Latin American strains by other mol ecular methods. Strains associated with two documented environmental r eservoirs exhibited three distinct ribotype patterns; those isolated f rom patients who ate food from the U.S. Gulf waters were all of riboty pe 2, while the strains related to the northeast Australian rivers wer e of ribotypes 9 and 10. Nontoxigenic V. cholerae 01 strains originati ng in latin America and the U.S. Gulf Coast did not form a specific cl uster of ribotypes. Ribotyping in combination with other well-defined methods can assist in epidemiologic investigations, helping to trace t he movement of strains and to identify their geographic origins.