Use of antiserum agar plates for serogrouping of meningococci

A convenient and reliable method for serogrouping meningococci, based on immunospecific precipitation haloes in antiserum-agar plates, is described. It gave concordant results with conventional slide-agglutination in 900 strains of groups A, B or C tested. The antiserum-agar can also be used as a primary isolation medium for detecting nasopharyngeal carriers of a certain serogroup if antibiotics are added.