Intrapartum polymerase chain reaction for detection of group B streptococcus colonisation

Lower vaginal swabs were collected to compare the intrapartum polymerase chain reaction (PCR) test to the standard antepartum culture for detection of group B streptococcus (GBS) colonisation.

Four hundred and forty-five pregnant women with documented antepartum GBS cultures, who did not receive either antepartum or intrapartum antibiotics, were included in this prospective study. At the time of delivery and before the intrapartum antibiotic prophylaxis (IAP), double swabs were collected, one of the swab was used in the GBS molecular-based (PCR) test and the other was processed for GBS culture in Ahmadi Hospital Clinical Laboratory. Neonates were examined after delivery to diagnose GBS sepsis, and using intrapartum GBS culture as gold standard test; the intrapartum PCR test was compared to the antepartum culture.

The sensitivity and specificity of antepartum culture to diagnose GBS colonisation were 73 & 95.5%, respectively, compared with 98.3% sensitivity & 99% specificity for intrapartum PCR test (P > 0.05). Although the intrapartum PCR test was more accurate (98.8%) for detection of GBS colonisation than antepartum culture (90%), its accuracy was significantly different. The neonatal GBS sepsis was significantly related to positive intrapartum cultures, and intrapartum PCR tests, but was not related to positive antepartum cultures (the IAP to the antepartum GBS-positive mothers reduces GBS sepsis of their neonates).

The intrapartum PCR test is an accurate bedside test and it has the potential to be used as intrapartum screening for GBS colonisation allowing appropriate management of mothers and neonates.