Capsular Types of Vibrio vulnificus: An Analysis of Strains from Clinical and Environmental Sources

Vibrio vulnificus produces a capsular polysaccharide (CPS) that is essential for virulence. CPS from V. vulnificus clinical strain MO6-24 has been purified and the structure determined. In preliminary screening with antisera raised to MO6-24 CPS, 4 (19%) of 21 clinical isolates (including MO6-24), but none of 67 environmental V. vulnificus isolates, agglutinated with anti-MO6-24 antisera (P = .003). CPS was isolated from a subset of 12 clinical and 7 environmental isolates and analyzed by high-performance anion-exchange chromatography and one-dimensional nuclear magnetic resonance. MO6-24 and 1 other serologically positive strain had identical CPS structures; the other 2 serologically positive strains had substitutions in two of four sugar residues. Thirteen other capsular types were identified among the remaining 15 strains from which CPS was extracted.