Accuracy of prenatal culture in predicting intrapartum group B streptococcus colonization status.

OBJECTIVE To evaluate the positive predictive value (PPV) of group B Streptococcus (GBS) cultures at 35-37 weeks of gestation relative to GBS colonization status at delivery. METHODS Rectovaginal swabs from 221 women at labor in four Lisbon hospitals were collected for GBS screening according to the CDC guidelines. RESULTS The PPV was 24.4%. IAP was administered to 100% of prenatally GBS positive women. There was no case of early onset GBS disease (EOD). CONCLUSIONS Poor accuracy of prenatal cultures in identifying true candidates for IAP highlights the need for Portuguese clinical and laboratory guidelines to prevent EOD and antibiotic overtreatment of pregnant women.