Intrapartum Vancomycin for Group B Streptococcus (GBS) Prophylaxis
Intrapartum Vancomycin for Group B Streptococcus (GBS) Prophylaxis
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.
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.
Inclusion Criteria:

 -  Women with documented GBS-positive antenatal screening culture or documented GBS
 bacteruria during pregnancy with plan to receive vancomycin for intrapartum antibiotic
 prophylaxis,

 -  ability to give informed consent,

 -  aged 18-48,

 -  English and or Spanish speaking, admitted in labor or undergoing induction of labor

 Exclusion Criteria:

 -  Inability to give consent,

 -  currently receiving antibiotics for another indication,

 -  recent antibiotic use (within the previous 7 days),

 -  allergy to vancomycin