Rapid diagnosis of acute bacterial meningitis by coagglutination and latex agglutination

Abstract

Early diagnosis and initiation of appropriate antimicrobial therapy is essential for the reduction of mortality and morbidity in acute pyogenic meningitis. The rapid diagnosis of meningitis by the detection of bacterial antigens in the cerebrospinal fluid (CSF) is now possible with the availability of commercially prepared kits. One hundred and eighty-six CSF samples were cultured for bacteria and examined for antigens of common organisms causing meningitis by a coagglutination technique (COA) and a latex agglutination test (LA). The COA had a concordance rate of 95·7% with culture while that of LA was 92·9%. The detection of Haemophilus influenzae type b antigens by both kits were in complete agreement with culture results ( 15 15 ). With Streptococcus pneumoniae antigens the COA was slightly more sensitive than the LA. With the Streptococcus group B antigen, however, both the tests proved to be oversensitive thus giving rise to false positives. Both kits failed to detect Neisseria meningitidis serogroup B exoantigens in two culture positive cases. Thus, while rapid diagnosis of acute bacterial meningitis by the detection of antigens in the CSF is extremely useful, negative results do not exclude the possibility of meningitis and positive results should be interpreted with the clinical picture and other laboratory parameters.