Management of GBS-Positive Woman in Labor at 36/37 Weeks
The correct answer is C: IV penicillin as soon as possible. This woman requires immediate intrapartum antibiotic prophylaxis with IV penicillin G (5 million units initially, then 2.5-3 million units every 4 hours until delivery) or IV ampicillin (2 g initially, then 1 g every 4 hours) to prevent early-onset neonatal GBS disease 1.
Why IV Antibiotics Are Essential
A positive GBS culture at 34 weeks remains valid and mandates intrapartum prophylaxis when labor begins. The CDC guidelines explicitly state that women with a positive GBS screen within the preceding 5 weeks should receive intrapartum antibiotic prophylaxis 1. Since this patient tested positive at 34 weeks and is now at 36/37 weeks (only 2-3 weeks later), her positive status is still current and actionable 1.
- Women with positive GBS vaginal-rectal screening cultures in late gestation during the current pregnancy require intrapartum antibiotic prophylaxis 1, 2
- The screening culture remains valid for 5 weeks from collection 1
- GBS-colonized women should receive intrapartum antibiotic prophylaxis when true labor begins 1
Why the Other Options Are Wrong
Immediate C-section (Option A) is not indicated. Cesarean delivery is not a treatment for GBS colonization and does not eliminate the need for prophylaxis if labor has begun or membranes have ruptured 1. The CDC specifically states that intrapartum prophylaxis is not routinely recommended only for cesarean deliveries performed before labor onset with intact membranes 1, 2.
Single dose oral amoxicillin (Option B) is completely inadequate. The CDC guidelines explicitly state that oral antibiotics alone are not adequate for GBS prophylaxis 1. Effective prophylaxis requires:
- Intravenous administration for adequate tissue and fetal blood levels 1, 3
- Multiple doses continued until delivery, not a single dose 1
- At least 4 hours of IV antibiotics before delivery for optimal neonatal protection 4, 5
Specific Treatment Protocol
Penicillin G remains the agent of choice:
- Initial dose: 5 million units IV 3, 4
- Maintenance: 2.5-3 million units IV every 4 hours until delivery 3, 4
- Ampicillin is an acceptable alternative: 2 g IV initially, then 1 g IV every 4 hours 3, 4
For penicillin-allergic patients:
- Low-risk allergy (no anaphylaxis history): Cefazolin 2 g IV initially, then 1 g IV every 8 hours 1, 3
- High-risk allergy (history of anaphylaxis, angioedema, respiratory distress, or urticaria): Clindamycin 900 mg IV every 8 hours (if susceptible) or vancomycin 1 g IV every 12 hours 1, 3
Critical Clinical Pitfalls to Avoid
Do not delay antibiotic administration. The goal is to achieve at least 4 hours of IV antibiotics before delivery to maximize neonatal protection 4, 5. Every hour of delay increases the risk of early-onset neonatal GBS disease, which carries significant morbidity and mortality 6, 7, 5.
Do not assume the prior lack of treatment invalidates the positive culture. The fact that she didn't receive treatment at 34 weeks is irrelevant—the positive culture result itself mandates action now that she is in labor 1. The CDC guidelines make no distinction between treated and untreated GBS-positive women; both require intrapartum prophylaxis 1, 2.
Do not use oral antibiotics or attempt outpatient treatment. Antepartum oral antibiotic treatment of GBS colonization is ineffective in eliminating carriage, does not prevent neonatal disease, and may promote antibiotic resistance 1, 3, 2. Treatment must occur intravenously during labor 1.
Impact on Neonatal Outcomes
Proper intrapartum prophylaxis dramatically reduces early-onset GBS disease. Without prophylaxis, the risk of vertical transmission and neonatal sepsis is substantial, with potential for severe complications including meningitis, pneumonia, and death 6, 7, 5. Intrapartum antibiotic prophylaxis has been the cornerstone of reducing early-onset GBS disease over the past three decades 7, 5.