The implementation of real-time PCR for detection of intrapartum GBS (group B Streptococcus) colonization as a way to reduce antibiotic prophylaxis usage.

The investigators intend to perform a cohort prospective trial in the delivery ward of CARMEL medical center. Pregnant women that are admitted to our ward and need to receive GBS (group B Streptococcus) prophylaxis either due to a positive GBS culture screen done at 35-37 weeks or by having risk factors for prophylactic antibiotic treatment (prolonged rupture of membranes, preterm delivery, GBS bacteriuria during current pregnancy) will be tested by a double vaginal swab (PCR and culture). Pregnant women that were screened positive at 35-37 weeks, those who had GBS bacteriuria during pregnancy and those who labor prematurely will be tested upon admission. Patients that have prolonged rupture of membranes (18 hours) will be tested by a double vaginal swab after 17 hours and prior to antibiotics administration.

All patient will be treated with GBS prophylactic antibiotics according to the culture screen done at 35-37 weeks or by risk factors (current protocol guidelines). Culture and PCR will be sent to the lab and the results will be revealed after delivery (the staff and patients will be blinded to the results of the culture and PCR until after delivery) in order to assess the number of patients that were treated with antibiotics unnecessarily.

The investigators intend to recruit 300 patients of which half will need antibiotics because of a positive culture at 35-37 weeks and half because of having risk factors. We decided to omit patients that will have fever during labor (a risk factor that necessitates GBS prophylaxis) because these patients will receive broad spectrum antibiotics anyway.

The vaginal double swab will be assessed by two different lab tests: The first one for GBS culture on selective media after enrichment of 16h and the second swab by the Cepheid Xpert GBS Assay performed on the GeneXpert Dx system which is a qualitative in vitro diagnostic test designed to detect GBS DNA from vaginal swab specimens, using fully automated real-time polymerase chain reaction (PCR).

inclusion criteria:

• Pregnant patients that were screened positive by a culture at 35-37 weeks (those patients will be screened with a vaginal double swab upon admission to labor ward).
• Pregnant patients with GBS bacteriuria in current pregnancy (those patients will be screened with a vaginal double swab upon admission to labor ward).
• Pregnant patients in preterm labor before 37 weeks (those patients will be screened with a vaginal double swab upon admission to labor ward).
• Pregnant patients with prolonged rupture of membranes (those patients will be screened with a vaginal double swab after 17 hours and prior to antibiotics treatment).
• All patients have signed an informed consent.

Exclusion Criteria:

• Pregnant patients that do not want to participate in the study.
• Pregnant patients that fever is the risk factor for GBS prophylaxis.
• Pregnant patients that were screened negative by a culture at 35-37 weeks.
• Pregnant patient with PPROM (before 34 weeks).

A cohort of 300 patient admitted to the labor ward in CARMEL medical center that need prophylactic antibiotics for GBS because of culture screen at 35-37 weeks or because of having risk factors.