Antibiotic prophylaxis with high-dose cefoxitin in bariatric surgery: an observational prospective single center study.

Background: The optimal dose of cefoxitin for antibiotic prophylaxis in obese patients remains uncertain. We evaluated the adequacy of a 4-gram dosing regimen of cefoxitin against the most frequent pathogens that infect patients undergoing bariatric surgery.
Methods: This observational prospective study included obese patients who required bariatric surgery and a 4-gram 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% ƒT _>4xMIC ). 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.
Results: Two hundred patients were included. The mean age of the patients was 46 (±12) years-old, and the mean 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% f T _>4xMIC ) of cefoxitin were 37.3%, 1.1% and 0% for S. aureus , Enterobacteriaceae and anaerobic bacteria, respectively. BMIs below 50 kg/m ² (OR 0.29, 95% CI [0.11-0.75], P = 0.0107 ) and a shorter duration of surgery (OR 0.97, 95% CI [0.95-0.99], P = 0.004 ) were associated with reaching the target concentrations.
Conclusions: In obese patients undergoing bariatric surgery, a regimen of 4 grams of cefoxitin led to an inadequate coverage for most common pathogens. A longer surgery duration and BMI over 50 kg/m ² increase the risk of underdosage.
(Copyright © 2019 American Society for Microbiology.)