Rapid detection of group B streptococci in vaginal swabs of parturients by latex particle agglutination.

Duplicate high vaginal swabs were obtained from 200 parturient women at Abeokuta (Nigeria). By culture on a selective agar twenty-two women (11%) were found to harbour group B streptococci. The second swab was subjected to a 45 min enzymatic extraction procedure and then tested in a latex agglutination test for group B streptococcal antigen (Wellcogen Strep B; Wellcome Diagnostics, Dartford, UK). The latex test permitted the detection of three out of 22 colonized women (overall sensitivity 13.6%). The sensitivity for detection of heavy colonization was 50% (three out of six women). It is concluded that the sensitivity of the method employed for rapid detection of group B streptococcal antigen in vaginal swabs is still unsatisfactory.