Su TY, et al. – This work was planned to assess the influence of current cefepime minimal inhibitory concentration (MIC) breakpoints and the maximal cefepime dose on treatment outcomes in patients with bacteremia caused by cefepime–susceptible Pseudomonas aeruginosa. Findings revealed that patients treated with cefepime for cefepime–susceptible P. aeruginosa bloodstream infections had a worse outcome while the isolates had a higher MIC value that was still within the susceptible category. In this study, a higher cefepime dose administration in cases with a MIC of <4 mg/L for P. aeruginosa improved patient outcomes. An increase in mortality rate was observed with a higher cefepime MIC (≥4 mg/L) for P. aeruginosa even with a maximal cefepime dose. Thus, when using cefepime to treat serious P. aeruginosa infections, the current CLSI (Clinical and Laboratory Standards Institute) cefepime MIC of 8 mg/L as the susceptibility breakpoint could not predict the clinical outcome well.

Methods

• Authors reviewed adult patients hospitalized between July 2010 and June 2014 with a positive blood culture for cefepime–susceptible P. aeruginosa and receipt of cefepime as the primary therapy throughout the course.
• They reviewed cefepime Etest MICs and clinical outcomes for P. aeruginosa bacteremia to identify the MIC breakpoint influencing treatment outcomes.

Results

• 90 patients were enrolled; 49 (54.4%) were male (mean age = 66.8 years).
• In this study, the mean Acute Physiology and Chronic Health Evaluation II score was 22.01.
• A maximal cefepime dose was administered to sixty patients (66.7%); the 30–day crude mortality rate was 36.7%.
• For P. aeruginosa, MIC₉₀ of cefepime was 8 mg/L.
• As per cumulative survival rate at 30 days, a lower cefepime MIC (<4 mg/L) for P. aeruginosa was associated with a higher survival rate than a higher MIC (≥4 mg/L) (72.6% vs. 23.5%, p < 0.0001).
• Findings suggested a cefepime MIC of ≥4 mg/L and age as independent risk factors for mortality, whereas the maximal cefepime dose was the independent protective factor.
• With the use of a maximal cefepime dose, there appeared no improvement in the outcomes of patients with P. aeruginosa bacteremia at a MIC of ≥4 mg/L.