Antibiotic Prophylaxis After C-Section Reduces Surgical Site Infections

Obese women who received oral cephalexin and metronidazole for 48 hours following cesarean delivery had a lower rate of surgical site infections compared with women who received placebo, according to results from a recent study published in the Journal of the American Medical Association.

In this single-center, randomized, double-blind clinical trial, researchers recruited 403 obese women (mean age 28; mean body mass index 39.7) who received either cephalexin 500 mg and metronidazole 500 mg (n=202) or placebo (n=201) every 8 hours for 48 hours following cesarean delivery. Randomization was stratified by membrane status prior to delivery, with 31.5% and 31.3% of the treatment and placebo groups having a ruptured membrane (ROM), respectively. All women received standard intravenous preoperative prophylactic cephalosporin (cefazolin 2 g). The researchers compared the rate of surgical site infections within 30 days of delivery between the 2 groups.

Among all participants, the rate of surgical site infections was 10.9% (95% CI, 7.9%-14.0%). The placebo group had a higher rate of surgical site infections compared with the antibiotic group (15.4% vs 6.4%; relative risk 0.41 [95% CI, 0.22-0.77]; P =.01).

Surgical site infections were more common in women with ROM compared with those who had intact membranes (19.8% vs 6.9%). In a post hoc analysis, the researchers noted that the difference in surgical site infection rates was greater when comparing only women with ROM prior to delivery (30.2% vs 9.5% for placebo vs treatment; P =.008).

No serious adverse events or allergic reactions were noted in either group.

Carri Warshak, MD, member of the Department of Obstetrics and Gynecology at the University of Texas Health Science Center and corresponding author on the study, attributed the high rate of surgical site infections among obese women to “bacterial microseeding that occurs in pregnancy and labor, especially after the membranes rupture.” She concluded that, “surgical site infections can be prevented with broad-spectrum antibiotics for a brief time after surgery until natural barriers are re-established.”

Related Articles


Valent AM, DeArmond C, Houston JM, et al. Effect of post–cesarean delivery oral cephalexin and metronidazole on surgical site infection among obese women: a randomized clinical trial. JAMA. 2017;318:1026-1034.