Activity of ceftaroline-avibactam tested against contemporary Enterobacteriaceae isolates carrying β-lactamases prevalent in the United States.

Contemporary (2012) β-lactamase-producing isolates (n=493) from U.S. hospitals were tested against ceftaroline-avibactam. Klebsiella spp., Escherichia coli and Proteus mirabilis isolates displaying the Clinical and Laboratory Standards Institute (CLSI) screening criteria for extended spectrum β-lactamase (ESBL) production were evaluated. Isolates carried genes encoding CTX-M (n=316, CTX-M-14-like and -15-like), KPC (n=45), CMY-2-like (n=54), or SHV enzyme with ESBL activity (n=78). Ceftaroline-avibactam inhibited 98.2% of the isolates at ≤0.5 μg/mL, and all strains were inhibited by ≤2 μg/mL of this novel β-lactamase-inhibitor combination. These results confirm that ceftaroline-avibactam could be a useful therapeutic option for Enterobacteriaceae isolates producing β-lactamases that are prevalent in the United States.