Murine monoclonal antibodies for detection of antigens and culture identification of Neisseria meningitidis group B and Escherichia coli K-1.

Four murine monoclonal antibodies which reacted with a (2----8)alpha-linked sialic acid polysaccharide were produced. Three of the antibodies reacted specifically with Neisseria meningitidis serogroup B and Escherichia coli K-1 polysaccharide antigens, whereas one antibody cross-reacted with N. meningitidis group C polysaccharide antigen, a (2----9)alpha-linked homopolymer of sialic acid. By using the most avid antibody (MB 62), a latex particle agglutination test was developed which could detect capsular polysaccharide at 10 ng/ml. It also detected antigen in the cerebrospinal fluid (CSF) of all seven N. meningitidis group B- and two E. coli K-1-infected patients, whereas 57 control CSF samples, including 8 from neonates, were negative. Cultures of 21 N. meningitidis group B strains, 7 E. coli K-1 strains, and 1 Moraxella nonliquefaciens strain gave a positive result, whereas 53 strains from other serogroups were all negative. In a separate clinical evaluation, the overall sensitivity of the latex particle agglutination test was 81% (22 of 27) with fresh CSF samples, 48% (15 of 31) with stored CSF samples, and 94% (32 of 34) with blood cultures. No false-positive reactions were recorded with 165 control CSF samples, and the specificity with blood cultures was 99.4% (519 of 522).