(65) Prophylactic Antibiotics after Cesarean Trial (PACT): A Randomized Control Trial

Objective:
A trial of postoperative antibiotics as prophylaxis for post-cesarean surgical site infections (SSI) noted a benefit in obese patients with ruptured membranes. However, this was before pre-incision extended antibiotic prophylaxis with adjunctive azithromycin. We sought to assess if 48-hour post-cesarean antibiotics reduce infectious morbidity in the era of extended pre-operative prophylaxis.


Study Design:
Between 8/2017 to 3/2023, we conducted a double-blinded randomized clinical trial that included obese patients undergoing cesarean with > 4 hours of ruptured membranes. section following the administration of extended-spectrum pre-operative prophylaxis. Participants with chorioamnionitis, immunosuppression, antibiotic contraindications, or planned post-operative antibiotics were excluded. Subjects were assigned randomly to cephalexin 500mg and metronidazole 500mg PO q8hrs for 48 hours post-operatively (cefalexin-metronidazole) vs. placebo (control). Per clinical practice, both groups received extended-spectrum pre-skin incision prophylaxis with cephazolin and azithromycin. The primary outcome was a composite of endometritis, SSI, or other post-cesarean infections within 30 days of delivery. Secondary outcomes included incisional morbidity, fevers, and other surgical wound complications. Analysis was performed by intention-to-treat as well as per protocol.



Results:
Among 321 randomized participants, 284 (88.4%) completed the 30-day follow-up. The median age was 27.8 years, and BMI was 38 kg/m2. Baseline characteristics were balanced between the 2 groups. There was no difference in the primary outcome between the active and placebo groups (5.0% vs 6.9%, RR 0.71, 95% CI, 0.26-1.91]. No significant differences were found between groups for other prespecified secondary outcomes, including rates of incisional morbidity, fever, wound separation, or endometritis (Table).



Conclusion:
The previously noted benefit of postoperative antibiotics for post-cesarean prophylaxis in obese patients was not seen in the pre-incision extended antibiotic regimen era. A larger trial is unlikely to find differences.