Antibiotic Administration in PPROM Primarily Prevents Neonatal Sepsis
The correct answer is B - Sepsis. Antibiotics given after PPROM primarily prevent neonatal sepsis by reducing vertical transmission of bacteria from mother to neonate and decreasing early-onset infectious complications. 1
Primary Mechanism of Antibiotic Benefit
The fundamental purpose of antibiotic prophylaxis in PPROM is to prevent vertical bacterial transmission and reduce neonatal infection risk. 1 When antibiotics are administered ≥4 hours before delivery, they are highly effective at preventing vertical Group B Streptococcus (GBS) transmission and early-onset GBS disease. 1 The duration of antibiotic exposure directly correlates with reduction in neonatal colonization and infection risk. 1
Evidence for Sepsis Prevention
Neonatal infection rates are significantly reduced with antibiotic therapy (RR 0.68,95% CI 0.53 to 0.87), representing a 32% reduction in neonatal sepsis. 2
In the landmark NICHD trial, overall sepsis was reduced from 15.6% to 8.4% (P=.01) in GBS-negative women receiving antibiotics, and pneumonia decreased from 7.0% to 2.9% (P=.04). 3
Antibiotics reduce chorioamnionitis (RR 0.57,95% CI 0.37 to 0.86), which directly impacts neonatal sepsis risk by preventing ascending infection. 2
Why Not RDS as the Primary Answer?
While antibiotics do reduce respiratory distress syndrome (RDS) rates (40.5% vs 48.7%, P=.04), 3 this is a secondary benefit mediated through pregnancy prolongation and reduced infection-related inflammation, not a direct pharmacologic effect. 3, 2 The mechanism is indirect:
- Antibiotics prolong pregnancy by reducing infection-triggered preterm labor 2
- Longer latency allows more fetal lung maturation 4
- Reduced chorioamnionitis decreases inflammatory lung injury 3
The direct, primary pharmacologic action of antibiotics is antimicrobial—preventing bacterial infection and sepsis. 1
Additional Neonatal Benefits (Beyond Sepsis)
Beyond sepsis prevention, antibiotics reduce:
- Necrotizing enterocolitis: 2.3% vs 5.8% (P=.03) 3
- Surfactant use: RR 0.83 (95% CI 0.72 to 0.96) 2
- Oxygen therapy requirements: RR 0.88 (95% CI 0.81 to 0.96) 2
- Abnormal cerebral ultrasound: RR 0.82 (95% CI 0.68 to 0.98) 2
Recommended Antibiotic Regimen
The standard regimen for PPROM at ≥24 weeks consists of:
- IV ampicillin 2g every 6 hours plus erythromycin 250mg every 6 hours for 48 hours 4, 1
- Followed by oral amoxicillin 250mg every 8 hours plus erythromycin 333mg every 8 hours for 5 additional days 4, 1
Critical Pitfall to Avoid
Never use amoxicillin-clavulanic acid, as it increases necrotizing enterocolitis risk (RR 4.60,95% CI 1.98 to 10.72). 2 Amoxicillin alone is safe. 1, 5