Impact of CLSI and EUCAST Cefepime breakpoint changes on the susceptibility reporting for Enterobacteriaceae.
- 2017
CONCLUSIONS: Lower cefepime MIC breakpoints decrease cefepime susceptibility for isolates harboring ESBLs, while sparing the majority of those with AmpCs. Copyright Published by Elsevier Inc. METHODS: Using Enterobacteriaceae susceptibility data from 2013 comparisons of MIC breakpoints were performed using Pearson's chi-squared test. Molecular testing on a subset of isolates was done. OBJECTIVE: We analyzed the effects of different cefepime MIC breakpoints on Enterobacteriaceae cefepime susceptibility and the presence of AmpC and extended-spectrum beta-lactamase (ESBL) genes within the cefepime MIC interpretative categories. RESULTS: Among 3784 non-duplicate clinical isolates, cefepime susceptibility decreased from 97.6% to 96.1% to 93.7% for CLSI 2013, CLSI 2014, and EUCAST 2011, respectively. In ceftriaxone non-susceptible isolates, cefepime susceptibility decreased from 79% to 66% (P<0.0001) using CLSI 2013 and 2014, respectively, which was greater and statistically significant for Escherichia coli and Klebsiella spp. but not for Enterobacter spp. (P=0.06). Isolates with MIC <=1mug/mL more often harbored AmpC (77%) than ESBL (18%) genes.