MOLECULAR CHARACTERIZATION OF VIBRIO-CHOLERAE O1 STRAINS BY PULSED-FIELD GEL-ELECTROPHORESIS

Pulsed-field gel electrophoresis (PFGE) was performed on 180 isolates of Vibrio cholerae serogroup 01 representing 6 different multilocus en zyme electrophoresis (MEE) types and 27 rRNA restriction fragment leng th polymorphism types (ribotypes). Isolates were digested with the res triction enzyme NotI and were separated into 63 patterns on the basis of differences in band arrangements. In general, strains which were di fferent by MEE or ribotyping also had different PFGE patterns. PFGE id entified individual strains within a single MEE type or ribotype; isol ates with one PFGE pattern were less frequently distinguished by ribot yping. All V. cholerae 01 isolates tested from the Latin American epid emic were indistinguishable by their MEE, ribotype, or PFGE patterns. PFGE could further distinguish strains of this same ribotype isolated in Africa, Europe, the South Pacific, or Southeast Asia. Although both MEE and PFGE could identify the strain from the Latin American epidem ic, PFGE was more rapid and less labor intensive. PFGE also distinguis hed nontoxigenic isolates endemic to the U.S. Gulf Coast from unrelate d nontoxigenic isolates. In the present study PFGE was more discrimina ting than other previously described subtyping assays for V. cholerae 01 and appears to be a useful epidemiologic tool.