Value of a rapid enzyme-linked immunosorbent assay for maternal vaginal group B Streptococcus colonization

Because group B streptococci maternal colonization is a risk factor for the development of neonatal sepsis, a commercially available rapid test was evaluated for its ability to detect intrapartum maternal colonization. A total of 180 paired vaginal swabs were cultured for group B streptococci and assayed by the Equate test. Of the 15 positive cultures, only 1 was detected by the Equate test, resulting in a sensitivity of 7% and a false-negative rate of 93%. The Equate test detected group B streptococci colonization only at a concentration of > or = 10(7) colony-forming units. These results indicate that the Equate test is not adequately sensitive for screening intrapartum populations for group B streptococci colonization.