A Retrospective Comparison of Antibiotic Regimens for Treatment of Chorioamnionitis

OBJECTIVE: To evaluate antibiotic regimens for the optimization of maternal and neonatal outcomes in pregnancies affected by chorioamnionitis. METHODS: A change in the standard antibiotic regimen for chorioamnionitis from ceftriaxone–metronidazole to ampicillin–tobramycin with the addition of metronidazole provided an opportunity to compare the outcomes of these antibiotic regimens in a real-world setting. This single-center retrospective cohort study included individuals with singleton gestations with a diagnosis of clinical chorioamnionitis who were treated with one of the two antibiotic regimens and who delivered after 24 0/7 weeks of gestation between January 1, 2019, and December 21, 2022, along with their neonates. Individuals with multiple gestations and terminations were excluded. Information about maternal and neonatal characteristics, labor and delivery, and chorioamnionitis diagnosis, as well as neonatal and maternal outcomes, was obtained through chart review. Logistic regression was done to calculate propensity scores for the antibiotic regimen, and the overlap weights method was used to balance the groups. Baseline characteristics included in the propensity score were compared using the standardized mean difference, with a value of at least 0.1 considered significant. Weighted risk differences were used to compare outcomes, with P <.05 considered significant. RESULTS: Overall, 459 maternal–neonatal dyads were identified and included in the analysis, with 276 receiving ceftriaxone–metronidazole and 183 receiving ampicillin–tobramycin. Although the groups initially differed on several characteristics, they were balanced after propensity score weighting. There was no difference in infectious maternal morbidity, postpartum hemorrhage, blood transfusion, admission to a monitored setting, or hysterectomy when ampicillin–tobramycin was compared with ceftriaxone–metronidazole. However, when neonatal outcomes were compared, a lower rate of early-onset neonatal sepsis was present in the group that received ampicillin–tobramycin (3.3% vs 11.1%; weighted risk difference −6.9%, 95% CI, −11.8 to −0.7, P <.01). Other secondary neonatal outcomes were not different. CONCLUSION: We conclude that ampicillin–tobramycin, with the addition of metronidazole for cesarean delivery, is a more appropriate empiric antibiotic choice to treat clinical chorioamnionitis due to reduced rates of early-onset neonatal sepsis when compared with ceftriaxone–metronidazole.