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). 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/m(2). 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/m(2) (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/m(2) increase the risk of underdosage. (This study was registered on ClinicalTrials.gov under identifier NCT03306290.)