Antimicrobial activity of ceftaroline and comparator agents when tested against numerous species of coagulase-negative Staphylococcus causing infection in US hospitals

A total of 1593 coagulase-negative staphylococci (CoNS) considered clinically significant were collected from 71 US medical centers in 2013-2014 and tested for susceptibility by CLSI broth microdilution methods. Species identification was performed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Overall, 59.7% of isolates were oxacillin resistant (MRCoNS). Ceftaroline (MIC50/90, 0.25/0.5 μg/mL) inhibited 99.2% of CoNS at ≤1 μg/mL (susceptible breakpoint for Staphylococcus aureus), including 98.7% of MRCoNS, and the highest ceftaroline MIC value was 2 μg/mL (13 isolates). Staphylococcus epidermidis represented 60.3% of the CoNS collection and was highly susceptible to ceftaroline (MIC50/90, 0.25/0.5 μg/mL, 99.9% inhibited at ≤1 μg/mL). All isolates of Staphylococcus capitis, Staphylococcus caprae, Staphylococcus hominis, Staphylococcus lugdunensis, Staphylococcus pettenkoferi, Staphylococcus simulans, and Staphylococcus warneri (MIC50/90, 0.06-0.25/0.25-0.5 μg/mL) were inhibited at ceftaroline MIC of ≤1 μg/mL. Staphylococcus haemolyticus represented only 4.8%, was atypically less susceptible to ceftaroline (MIC50/90, 0.5/2 μg/mL, 87.0% inhibited at ≤1 μg/mL), and accounted for 76.9% (10/13) of isolates with ceftaroline MIC >1 μg/mL.