Effect of Obesity on Clinical Outcomes of Patients Treated With Cefepime

Background: As the prevalence of obesity climbs, dosing of antimicrobials, particularly cephalosporins, is becoming a greater challenge for clinicians. Data are lacking for appropriate dosing of cefepime, an anti-pseudomonal cephalosporin that is widely used as an empiric anti-pseudomonal agent. Objective: The purpose of this study was to determine the rate of clinical treatment failure in obese patients compared with nonobese patients receiving cefepime as definitive monotherapy. Methods: Adult inpatients treated with cefepime monotherapy for ≥72 hours were included. Patients were excluded if they (1) were not able to achieve culture clearance within 72 hours and (2) had polymicrobial infections requiring more than one antibiotic for definitive therapy. Results: Fifty-eight obese patients and 56 nonobese patients were included. Pseudomonas aeruginosa, Escherichia coli, and Enterobacter spp were the most prevalent organisms isolated. Most organisms had a minimum inhibitory concentration of ≤1 µg/mL to cefepime with no differences in minimum inhibitory concentration distributions between groups. Definitively, 60% of patients received cefepime 1 g, while almost 40% received cefepime 2 g. Clinical failure occurred in 52% of patients (67% obese vs 36% nonobese; P = .001), with study group (odds ratio = 1.057, 95% confidence interval = 1.008-1.109) and respiratory source (odds ratio = 3.251, 95% confidence interval = 1.378-7.667) being independent predictors of failure. There were no differences in hospital length of stay, all-cause mortality, or 30-day readmissions. Conclusions: Obese patients treated with cefepime are more likely to experience treatment failure than nonobese patients. Larger trials examining the reasons for clinical failure in obese patients treated with cefepime are needed to confirm the findings from this preliminary work.