Intrapartum detection of Group B Streptococci (GBS) by point of care (POCT) real time PCR testing

Introduction:

Intrapartum antibiotic prophylaxis (IAP) of pregnant women colonized with GBS was established to prevent GBS transmission and consecutive early onset sepsis of neonates. As colonization status varies the best time for screening is few hours before delivery. Real-time PCR with POCT is now available for intrapartum testing in < 2 hours.

Aims:

We directly compared real time GBS-PCR (GenePOC) with standard culture. Second, we compared GBS detection provided by outpatient antenatal culture-based analysis and intrapartum screening directly before delivery.

Material and methods:

Rectovaginal swabs of 300 pregnant women were tested by culture with solid media and LIM-broth on the one hand and by PCR on the other hand. PCR was performed from direct swabs and LIM-broth cultures. Comparison between antenatal and intrapartum testing was performed for 133 patients (44%).

Results:

PCR from direct swabs was characterized by high sensitivity (95,8%) and specificity (95,5%). The detection rates could not be increased by LIM-Broth. 11 (3,7%) patients with GBS colonization were detected by PCR only whereas 2 patients remained PCR negative with positive culture. Comparison between antenatal and intrapartum screening revealed unchanged colonization status for most patients but for 15% the colonization status changed. 11% became GBS negative and 4% GBS positive as compared to antenatal testing.

Conclusion:

The European consensus conference recommended intrapartum GBS-screening for better selection of patients for IAP. If GBS-screening with intrapartum GBS-PCR was implemented 4% of patients were found with previously undetected GBS colonization while 11% with positive antenatal screening remained negative by intrapartum testing.