SAFETY AND IMMUNOGENICITY OF A POLYVALENT ESCHERICHIA-COLI VACCINE IN HUMAN VOLUNTEERS

Since a limited number of O serogroups account for nearly 70% of bacteremic and meningitic Escherichia coli isolates, a polyvalent vaccine was made by conjugating a Pseudomonas aeruginosa exotoxin A carrier protein to the O polysaccharide of 12 serogroups off. coli (O1, O2, O3, O6-O8, O12, O15, O16, O18, O25, O75). No serious reactions occurred in 88 vaccinees. Fourfold or greater increases in ELISA antibody levels over baseline were greatest (> 60% of vaccinees) for O1, O2, O6-O8 and O15; intermediate (similar to 50%) for O18 and O75, and poorest (greater than or equal to 45%) for O4, O12, O16, and O25. Responses with functionally active opsonophagocytic antibody generally paralleled ELISA antibody responses. With the availability of a safe, immunogenic E. coli vaccine, active and passive immunization strategies merit further development as adjunctive treatment for E. coli bacteremia and neonatal meningitis.