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Antibiotics reduce post-pregnancy infections in women with pre-pregnancy obesity

Among women who were obese before undergoing cesarean delivery, those who received cephalexin and metronidazole for 48 hours after delivery had fewer surgical site infections than their counterparts who took placebo, according to findings recently published in JAMA.

“Obesity is associated with increased risk of surgical site infection following cesarean delivery,” Amy M. Valent, DO, of the department of obstetrics and gynecology at Oregon Health and Science University, and colleagues wrote. “The optimal perioperative antibiotic prophylactic regimen in this high-risk population undergoing cesarean delivery is unknown.”

Researchers assessed data from women who had a pre-pregnancy BMI of 30 kg/m² or greater and had received standard IV preoperative cephalosporin prophylaxis. After cesarean delivery, women randomly received either 500 mg of cephalexin and metronidazole (n = 202) or an identical-looking placebo (n = 201) every 8 hours for 48 hours. The primary outcome was surgical site infection, which consisted of any organ/space, superficial incisional or deep incisional infections within 30 days of cesarean delivery.

Valent and colleagues found that the primary outcome occurred in 10.9% (95% CI, 7.9-14) of participants. In analysis by group, surgical site infection was significantly reduced in the antibiotic group vs. the placebo group (6.4% vs. 15.4%; RR = 0.41; 95% CI, 0.22-0.77).

“Among the secondary outcomes measured, patients treated with cephalexin-metronidazole had lower rates of cellulitis but no significant decrease in other secondary outcomes, including rates of incisional morbidity, fever of unknown etiology, wound separation or endometritis,” the researchers wrote, adding that there were no allergic reactions or other serious adverse events reported in either group.

“Recognizing the maternal and neonatal benefit of breastfeeding, the lack of known neonatal adverse effects, and maternal reduction in [surgical site infections], the benefit of this antibiotic regimen likely outweighs the theoretical risks of breast milk exposure in the obese population,” Valent and colleagues wrote.

In a related editorial, David P. Calfee, MD, MS, and Amos Grünebaum, MD, both of Weill Cornell Medicine, wrote that the findings should not be interpreted as appropriate to all women.

“Additional studies are needed to confirm these findings and to determine if there are specific subpopulations within this group to whom the benefit is limited to avoid unnecessary antibiotic exposure and its associated risks among those unlikely to benefit,” the authors wrote. “Furthermore, despite the apparent effectiveness of the intervention, the rate of [surgical site infections] observed among women assigned to the postoperative antimicrobial prophylaxis group of the study was higher than that typically observed among nonobese women. This finding is important because it highlights that this strategy is not a panacea, that obese women remain at high risk of infectious complications, and that additional strategies to mitigate this risk are needed.” – by Janel Miller

Disclosure: Calfee reports he has received grants from Merck, Sharp and Dohme. The researchers and Grünebaum report no relevant financial disclosures.