O-ANTIGEN SEROEPIDEMIOLOGY OF KLEBSIELLA CLINICAL ISOLATES AND IMPLICATIONS FOR IMMUNOPROPHYLAXIS OF KLEBSIELLA INFECTIONS

To provide a database for the development of an O-antigen-polysacchari de-containing vaccine against Klebsiella spp., we examined the O-antig en seroepidemiology of 378 Klebsiella clinical isolates collected pros pectively in two university centers, Strains were typed by competitive enzyme-linked immunosorbent assay with rabbit antisera specific for s erogroups O1 to O12 and monoclonal antibodies (MAbs) specific for sero groups O1, O2ab, O2ac, and the genus-specific core antigen, The number s of isolates (percentages) of individual O serogroups were as follows : 148 (39.2) for serogroup O1, 40 (10.6) for serogroup O2ab, 4 (1.1) f or serogroup O2ac, 89 (23.6) for serogroup O3, 2 (0.5) for serogroup O 4, 32 (8.5) for serogroup O5, none for serogroups O7, O9, and O12, and 21 (5.6) for serogroup O11. Forty-two (11.1) of the strains mere non- O-typeable. O-serogroup distributions were virtually identical between isolates from invasive infections and those from noninvasive infectio ns or colonizations. A vaccine containing the O-specific polysaccharid es of serogroups O1, O2ab, O3, and O5 would cover 52% of clinically oc curring O-antigen specificities, Three hundred thirty-eight of 378 iso lates (89.4%) reacted with the genus-specific MAb V/9-5, which recogni zes an epitope of the outer core region of Klebsiella lipopolysacchari de. Antibodies directed against this epitope may represent a further a lternative for O-antigen-targeted immunoprophylaxis of Klebsiella infe ctions, These data support further experimental investigations on the protective potential of O-antigen-based vaccines and/or hyperimmune gl obulins in Klebsiella infection.