Evaluation of two enzyme immunoassays for rapid detection of group B streptococci in pregnant women

Abstract

The performance of two enzyme immunoassays for rapid detection of group B streptococci (GBS) was evaluated in comparison to culture using cervical swabs from 191 pregnant women. Ten percent of the women harboured GBS. There were two positive results in the Icon assay (Hybritech), both in women with heavy growth in the culture, and four positive results in the Quidel assay (Quidel), two in the women with heavy colonization and one each in women with moderate and light growth of GBS respectively. The sensitivity of both assays was low, being 11% (2/18) for the Icon assay and 24% (4/17) for the Quidel assay. The specificity of both assays was 100%. Both assays could detect > or = 10(6) group B streptococci per swab. A positive result justifies ampicillin prophylaxis due to the high risk for the newborn. A negative result should be confirmed by rapid culture techniques.

Group B streptococcus: rapid intraparturn detection and influence of density of maternal colonization on vertical transmission

“…However, as previously reported by Gentry et al [8], the immunoassay sensitivity for heavy vaginal colonization is quite acceptable, while a sensitivity of 6.5% for light vaginal colonization is inadequate [5]. In the same way, Wüst et al [9] reported a sensitivity of 11% for the ICON test which was increased for heavy colonization (≥10 6 CFU/mL).…”