Activity of Ceftaroline-Avibactam Tested Against Multidrug-Resistant Enterobacteriaceae and Methicillin-Resistant Staphylococcus aureus Collected from USA Hospitals in 2011

• Among 337 Enterobacter spp. strains, 97.3% were inhibited by ceftarolineavibactam at ≤0.5 mg/L. Meropenem (MIC 90, ≤0.06 mg/L; 99.4% susceptible) and tigecycline (MIC 50/90, 0.25/0.5 mg/L; 98.5/95.3% susceptible by CLSI/EUCAST breakpoint criteria) were also very active against Enterobacter spp. (Table 2). Among ceftazidime-non-susceptible (MIC, ≥8 mg/L) Enterobacter spp. strains, 85.0 and 96.7% of strains were inhibited at ceftaroline-avibactam MIC of ≤0.5 and ≤1 mg/L, respectively (Tables 1 and 2) • Ceftaroline-avibactam inhibited all 150 P. mirabilis strains at ≤0.25 mg/L (MIC 50/90, 0.06/0.12 mg/L). Ceftaroline-avibactam was also active against Serratia marcescens (MIC 50/90 , 0.5/1 mg/L), with 89.9 and 98.7% of strains being inhibited at MIC of ≤0.5 and ≤1 mg/L, respectively (Tables 1 and 2)