Observational, Prospective Single-Center Study of Antibiotic Prophylaxis with High-Dose Cefoxitin in Bariatric Surgery

The optimal dose of cefoxitin for antibiotic prophylaxis in obese patients remains uncertain. We evaluated the adequacy of a 4-g dosing regimen of cefoxitin against the most common pathogens that infect patients undergoing bariatric surgery. This observational prospective study included obese patients who required bariatric surgery and a 4-g dose of cefoxitin as an antibiotic prophylaxis. Serum concentrations were measured during surgery (incision, wound closure, and in case of reinjection). ABSTRACT The optimal dose of cefoxitin for antibiotic prophylaxis in obese patients remains uncertain. We evaluated the adequacy of a 4-g dosing regimen of cefoxitin against the most common pathogens that infect patients undergoing bariatric surgery. This observational prospective study included obese patients who required bariatric surgery and a 4-g dose of cefoxitin as an antibiotic prophylaxis. Serum concentrations were measured during surgery (incision, wound closure, and in case of reinjection). The pharmacokinetic/pharmacodynamic (PK/PD) target was to obtain free cefoxitin concentrations above 4× MIC, from incision to wound closure (100% fT>4×MIC). The targeted MIC was based on the worst-case scenario (the highest ECOFF value of Staphylococcus aureus, Enterobacteriaceae, and anaerobic bacteria). The secondary outcomes were the factors related to underdosage. A total of 200 patients were included. The mean age of the patients was 46 ± 12 years old, and the mean body mass index (BMI) was 45.8 ± 6.9 kg/m2. Bypass surgery was the preferred technique (84%). The percentages of patients who met the PK/PD target (100% fT>4×MIC) of cefoxitin were 37.3, 1.1, and 0% for S. aureus, Enterobacteriaceae and anaerobic bacteria, respectively. BMIs below 50 kg/m2 (odds ratio [OR] = 0.29, 95% confidence interval [CI] = 0.11 to 0.75, P = 0.0107) and a shorter duration of surgery (OR = 0.97, 95% CI = 0.95 to 0.99, P = 0.004) were associated with reaching the target concentrations. In obese patients undergoing bariatric surgery, a regimen of 4 g of cefoxitin led to an inadequate coverage for most common pathogens. A longer surgery duration and a BMI of >50 kg/m2 increase the risk of underdosage. (This study was registered on ClinicalTrials.gov under identifier NCT03306290.)