Selection during Cefepime Treatment of a New Cephalosporinase Variant with Extended-Spectrum Resistance to Cefepime in an Enterobacter aerogenes Clinical Isolate

摘要

Enterobacter aerogenes resistant to cefepime (MIC, 32 μg/ml) was isolated from a patient treated with cefepime for an infection caused by a strain of E. aerogenes overproducing its AmpC β-lactamase (MIC of cefepime, 0.5 μg/ml). The AmpC β-lactamase of the resistant strain had an L-293-P amino acid substitution and a high kcat/Km ratio for cefepime. Both of these modifications were necessary for resistance to cefepime.