Intrapartum group B Streptococcus screening using real-time polymerase chain reaction in Japanese population.

OBJECTIVE: The objective of this study was to analyze the diagnostic accuracy of a commercial real-time polymerase chain reaction (PCR) assay for group B streptococcus (GBS) colonization status and to compare results of the intrapartum PCR with the antepartum conventional GBS culture in Japanese pregnant women.

METHODS: This prospective observational study enrolled Japanese pregnant women at 35-37 weeks' gestation. Paired recto-vaginal swabs were obtained for PCR and conventional culture, both at 35-37 weeks' gestation and at admission for delivery. Performance of PCR was analyzed by comparing with the culture results. Furthermore, using the intrapartum culture results as the gold standard, the test of both the antepartum culture and the intrapartum PCR were characterized.

RESULTS: We prospectively enrolled 79 pregnant women at 35-37 weeks' gestation, and the intrapartum results were obtained from 73 of those women. The sensitivity of PCR was 86.2%, and concordance rate with the conventional culture was 96.7% overall. Compared with the intrapartum culture, the sensitivity and the specificity of the intrapartum PCR were 83.3% and 98.4%, respectively, while the sensitivity and the specificity of the antepartum culture were 100.0% and 95.1%.

CONCLUSIONS: The intrapartum real-time PCR assay for GBS screening has the accuracy similar to the antepartum conventional culture method.