Adjunctive Azithromycin Prophylaxis for Prelabor Cesarean Birth

To evaluate maternal postoperative infections before and after addition of adjunctive azithromycin to standard antibiotic prophylaxis for prelabor cesarean births. We conducted a retrospective cohort study of patients with singleton gestations at more than 23 weeks of gestation who underwent prelabor cesarean birth at a single tertiary care center. Deliveries were categorized as those before implementation of 500 mg intravenous azithromycin in addition to standard preoperative cephalosporin antibiotic prophylaxis (pre-AZI group; January 2013-September 2015) and those after implementation of adjunctive azithromycin (post-AZI group; January 2016-December 2018). Cesarean births from October to December 2015 were excluded as a washout period. The primary outcome was a composite of postcesarean infections (endometritis, superficial or deep wound infections, intra-abdominal abscess, urinary tract infections). Secondary outcomes included composite components, other wound or postoperative complications, and select neonatal morbidities. Outcomes were compared between groups, and adjusted odds ratios (aORs) and 95% CIs were calculated using multivariable analysis. Propensity score matching was performed to assess the robustness our analysis. Of 2,867 delivering patients included for analysis, 1,391 (48.5%) were in the pre-AZI group and 1,476 (51.5%) were in the post-AZI group. Patients in the post-AZI group were older and were more likely to have private insurance, use aspirin, and receive predelivery antibiotics within 2 weeks. There were significantly lower odds of composite infection after azithromycin implementation (3.3% vs 4.8%, aOR 0.60, 95% CI 0.40-0.89), driven by a reduction in wound infection odds (2.4% vs 3.5%, aOR 0.61, 95% CI 0.39-0.98). There were lower odds of other postpartum complications, including wound seroma (0.5% vs 0.9%, aOR 0.34, 95% CI 0.13-0.90) and dehiscence (0.5% vs 1.2%, aOR 0.32, 95% CI 0.13-0.79). There were no differences in select neonatal morbidities between groups. Of 1,138 matching sets in the propensity analysis, the primary outcome remained significantly lower in the post-AZI group (aOR 0.64, 95% CI 0.41-0.99). Adopting adjunctive azithromycin for prelabor cesarean deliveries was associated with lower odds of postpartum infection.