Introduction: Our institution previously infused cefepime as an intermittent intravenous (IV) infusion but changed to IV push dosing due to drug shortages. The impact of this change has not been evaluated and may affect pharmacokinetic targets for cefepime, particularly in populations with hyperdynamic pharmacokinetics. We sought to evaluate bacterial resistance patterns post-cefepime exposure in a burn unit. Methods: Adult patients admitted to the burn, trauma, or plastic surgery services with a physical location in our burn unit were retrospectively evaluated if they received 3 or more consecutive doses of cefepime from June 2023 to May 2024. Patients also required at least one culture obtained post-cefepime exposure for inclusion. The primary outcome was the incidence of patients with resistant or intermediate pathogens after cefepime exposure. Secondary outcomes included time to resistance and rate of other antipseudomonal antibiotic resistance. Results: Sixty-one patients were included with a median total body surface area burn of 9.75%, age of 56, weight of 83 kg, and admission creatinine of 1.1 mg/dL. The median dose was 2000 mg with 83% of patients receiving every 8-hour regimen for a median duration of 5 days. Thirteen patients had multiple cefepime exposures and 47 patients had 1 or more pathogens isolated prior to or on the date of cefepime exposure. Eighteen (29.5%) patients developed cefepime resistance to gram negative (GN) bacteria after exposure. Three (6.6%) patients had cefepime intermediate GN bacteria which all became cefepime resistant bacteria. Three (4.9%) patients had cefepime resistant bacteria prior to exposure. The most common resistant bacteria was Pseudomonas aeruginosa, obtained from 11 patients. The median time to bacterial resistance was 14.5 days (IQR 7-68). All patients with cefepime resistant bacteria developed resistance to other antipseudomonal antibiotics. Conclusions: Development of cefepime-resistant bacteria is prevalent in our burn unit. Cefepime resistance was especially problematic among Pseudomonas pathogens and appeared to be associated with other antipseudomonal antibiotic resistance. IV push administration may contribute to this resistance.
Buckley et al. (Sun,) studied this question.