Mohammed R Khalil1, Niels Uldbjerg2, Poul B Thorsen3, Jens K Møller4. 1. Department of Obstetrics and Gynecology, Lillebaelt Hospital, Kolding, Denmark. 2. Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark. 3. Research Unit for Gynecology and Obstetrics, Department of Clinical Research, University of Southern Denmark, Odense, Denmark. 4. Department of Clinical Microbiology, Lillebaelt Hospital, Vejle, Denmark.
Abstract
OBJECTIVE: To compare a risk-based and culture-based screening approach for identification of group B streptococci (GBS) vaginal colonization using an intrapartum rectovaginal culture as the reference standard. METHODS: Pregnant women attending the prenatal clinic at Lillebaelt Hospital, Kolding, Denmark, between April 1, 2013, and June 30, 2014, were invited to participate in a prospective observational study. For prepartum culture-based screening, vaginal and rectal culture samples were obtained and, for reference, standard, paired vaginal and rectal culture samples were collected during labor. Risk factors for risk-based screening were previous early-onset GBS, GBS bacteriuria during pregnancy, maternal temperature ≥38.0°C intrapartum, and rupture of membranes for more than 18 hours. RESULTS: The intrapartum rectovaginal GBS colonization rate was 30% (32/108) among participants with risk factors and 15% (123/794) among participants without risk factors. Culture-based screening demonstrated a sensitivity, specificity, positive predictive value, negative predictive value, and positive likelihood ratio in predicting intrapartum GBS carriage of 78% (95% confidence interval [CI] 71-84), 95% (94-97), 78% (70-84), 95% (94-97), and 17 (12-23), respectively; for risk-based screening, these values were 21% (15-28), 90% (87-92), 30% (22-38), 85% (83-86), and 2 (1-3), respectively. CONCLUSIONS: Culture-based screening performed considerably better than a risk-based approach in identifying intrapartum GBS colonization.
OBJECTIVE: To compare a risk-based and culture-based screening approach for identification of group B streptococci (GBS) vaginal colonization using an intrapartum rectovaginal culture as the reference standard. METHODS: Pregnant women attending the prenatal clinic at Lillebaelt Hospital, Kolding, Denmark, between April 1, 2013, and June 30, 2014, were invited to participate in a prospective observational study. For prepartum culture-based screening, vaginal and rectal culture samples were obtained and, for reference, standard, paired vaginal and rectal culture samples were collected during labor. Risk factors for risk-based screening were previous early-onset GBS, GBS bacteriuria during pregnancy, maternal temperature ≥38.0°C intrapartum, and rupture of membranes for more than 18 hours. RESULTS: The intrapartum rectovaginal GBS colonization rate was 30% (32/108) among participants with risk factors and 15% (123/794) among participants without risk factors. Culture-based screening demonstrated a sensitivity, specificity, positive predictive value, negative predictive value, and positive likelihood ratio in predicting intrapartum GBS carriage of 78% (95% confidence interval [CI] 71-84), 95% (94-97), 78% (70-84), 95% (94-97), and 17 (12-23), respectively; for risk-based screening, these values were 21% (15-28), 90% (87-92), 30% (22-38), 85% (83-86), and 2 (1-3), respectively. CONCLUSIONS: Culture-based screening performed considerably better than a risk-based approach in identifying intrapartum GBS colonization.