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A simple trivalent colour test, developed for the rapid detection and identification of streptococci belonging to Lancefield groups A, C and G, was evaluated for sensitivity and specificity with cultures and when directly used with wound and throat swabs. In tests performed on cultures, all of 94 group A, 78 group C and 94 group G cultures were correctly identified. In direct tests on wound swabs, 49 of 52 group A, 17 of 19 group C and 48 of 51 group G streptococci were detected and correctly identified; no false positives were observed. With throat swabs from pharyngitis patients 34 of 36 group A, 3 of 6 group C and 5 of 8 group G streptococci gave positive results. Almost 10% of these swabs gave false positive reactions with the group C component of the test system. Samples taken from uninfected individuals indicated that the false positives were probably associated with blood group A. The test system gives rapid and reliable results with streptococcal cultures, but when directly applied to clinical samples the results must be interpreted with caution, particularly if the patient's blood group is not known.

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Four murine monoclonal antibodies which reacted with a (2->8)a-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)a-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 Band 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 Moraxela 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).