Intrapartum Vancomycin for Group B Streptococcus (GBS) Prophylaxis
Condition: GBS Positive; Women in Labor Given Vancomycin for Prophylaxis
Study type: Observational

Summary: 
      While it is clear that intrapartum antibiotics reduce neonatal GBS infection rates, the
      mechanism by which these drugs prevent neonatal GBS is not well established. One postulated
      theory is antibiotics work to reduce bacterial load in the birth canal; thus decreasing fetal
      exposure during labor and delivery. To our knowledge, the relationship between vancomycin and
      vaginal GBS colony counts has never been studied. In this prospective cohort study, our
      objective is to determine the relationship between intrapartum IV vancomycin and vaginal GBS
      colony counts.
    

Detailed description: 
      Charts of patients presenting for induction of labor will be reviewed for potential
      eligibility. After provider permission, eligible patients will be approached for screening
      who are presenting for induction with documented GBS positivity and plan for vancomycin for
      intrapartum antibiotic prophylaxis. Patients presenting to the emergency room for labor
      evaluation/labor evaluation/pre-term labor evaluation, may be pre-screened for potential
      eligibility. Patients subsequently admitted in labor/preterm labor or with rupture of
      membranes with documented GBS positivity and plan for vancomycin for intrapartum antibiotic
      prophylaxis will be approached for screening. Additionally pharmacy will alert study staff
      when a patient is admitted to the labor floor or antenatal care unit and vancomycin has been
      ordered for antibiotic prophylaxis. These patients will then be approached for screening

      Data collection: Demographic information such as age, race, date of initial GBS culture and
      time of rupture of membranes will be abstracted from enrolled patients' charts. Intrapartum
      vaginal cultures will be collected with a vaginal swab from the distal vagina by trained
      obstetrics and gynecology residents, attendings, nurses, nurse midwives and nurse
      practitioners prior to the initiation of antibiotics and at two hour intervals until delivery
      or after eight hours has elapsed.

      Swabs will be transported to the lab. Colony counts will be determined via serial dilution.
      Specimens will be diluted in sterile saline and inoculated onto Columbia Agar containing 5%
      sheep blood, colistin (10 mg), and nalidixic acid (10 mg/L). After incubation for 48 hours at
      35 C in ambient air, the number of colonies on the dilution plates will be visually counted
      and multiplied by the appropriate dilution factor for that particular plate.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Women with documented GBS-positive antenatal screening culture or documented GBS bacteruria
        during pregnancy with plan to receive vancomycin for intrapartum antibiotic prophylaxis
      
Biospecimen description: 
      vaginal swabs collected during labor plated for GGBS bacteria and then discarded
    
Keywords: vancomycin, GBS