IV Triple Antibiotic Regimen for Chorioamnionitis
The recommended IV antibiotic regimen for chorioamnionitis is ampicillin (2g IV initial dose, then 1g IV every 4 hours) plus gentamicin (5 mg/kg IV daily dose), with the addition of clindamycin (900mg IV) at umbilical cord clamping in case of cesarean delivery. 1
First-Line Antibiotic Regimen
The Infectious Diseases Society of America and the Centers for Disease Control and Prevention (CDC) recommend the following empirical antibiotic therapy for chorioamnionitis:
- Ampicillin: 2g IV initial dose, then 1g IV every 4 hours
- Gentamicin: 5 mg/kg IV daily dose (once-daily dosing)
- Clindamycin: 900mg IV when the umbilical cord is clamped if cesarean delivery is performed 1, 2
Recent evidence supports daily dosing of gentamicin rather than traditional three-times-daily dosing for greater efficacy and decreased fetal toxicity 3. A 2019 study demonstrated that daily gentamicin dosing using ideal body weight was associated with a 64% lower risk of postpartum endometritis and a 5% greater chance of successful outcome compared to traditional 8-hour dosing regimens 4.
Alternative Regimens for Penicillin Allergy
For patients with penicillin allergy, the CDC recommends:
- Low risk of anaphylaxis: Cefazolin 2g IV initial dose, then 1g IV every 8 hours
- High risk of anaphylaxis: Vancomycin 1g IV every 12 hours, and clindamycin 900mg IV every 8 hours (if the GBS isolate is confirmed susceptible) 1
Broader Spectrum Coverage When Indicated
For cases requiring additional coverage beyond standard regimens, particularly with suspected polymicrobial infection or resistant organisms, broader spectrum agents may be considered:
- Piperacillin/tazobactam (Zosyn) is suggested by the CDC for treatment of chorioamnionitis when broader coverage is needed 1
Duration of Antibiotic Therapy
Evidence supports a limited course of antibiotics for chorioamnionitis:
- For vaginal deliveries: One additional dose of antibiotics postpartum is sufficient for immune-competent women with chorioamnionitis 5, 6
- For cesarean deliveries: Some patients may benefit from a more extended course of antibiotic therapy, particularly those who are obese or had prolonged labor or rupture of membranes 6
A 2003 study found that when treated promptly intrapartum, one additional dose of antibiotics postpartum was sufficient therapy for immune-competent women with chorioamnionitis, with no significant difference in treatment failure rates compared to continuing antibiotics until the patient was afebrile and asymptomatic for 24 hours 5.
Neonatal Considerations
All newborns of mothers with chorioamnionitis should receive:
- Limited diagnostic evaluation (blood culture, complete blood count with differential and platelet count)
- Empirical antimicrobial therapy with ampicillin and gentamicin 7, 1
- Observation in the hospital for at least 48 hours 1
Clinical Pearls and Pitfalls
- Do not delay delivery once chorioamnionitis is diagnosed, regardless of gestational age 2
- Vaginal delivery is preferred when possible; cesarean delivery should be reserved for standard obstetrical indications 2, 3
- Patients with chorioamnionitis may require higher doses of oxytocin to achieve adequate uterine activity 2
- Antipyretic agents (mainly acetaminophen) can be administered, though evidence for their benefits is limited 2
- Corticosteroids for fetal lung maturation and magnesium sulfate for neuroprotection should still be considered between 24 0/7 and 33 6/7 weeks of gestation, but delivery should not be delayed to complete the full course 2