Antimicrobial activity of ceftaroline combined with avibactam tested against bacterial organisms isolated from acute bacterial skin and skin structure infections in United States medical centers (2010-2012)

Ceftaroline-avibactam and comparator agents were tested against clinical isolates collected at 174 medical centers from patients with acute bacterial skin and skin structure infection (ABSSSI) in the United States (USA) during 2010-2012. Isolates were processed at the medical centers and forwarded to a central laboratory for confirmatory identification and susceptibility testing using reference methods. Ceftaroline-avibactam was highly active against methicillin-susceptible (MIC50/90, 0.25/0.25 μg/mL) and methicillin-resistant Staphylococcus aureus (MRSA; MIC50/90, 0.5/1 μg/mL). Vancomycin, tigecycline, daptomycin, and linezolid were also active (>99.9% susceptible) against MRSA (51.4% of S. aureus), but activity against MRSA was decreased for erythromycin, levofloxacin, and clindamycin (10.8, 40.3, and 81.9% susceptible, respectively). β-Hemolytic streptococci were highly susceptible to β-lactam antimicrobials, including ceftaroline-avibactam (MIC50/90, ≤0.03/≤0.03 μg/mL). Ceftaroline-avibactam was very active against Escherichia coli and Klebsiella pneumoniae (MIC50/90, 0.03/0.06 and 0.06/0.25 μg/mL, respectively) including extended-spectrum β-lactamase (ESBL) screen-positive phenotypes (MIC50/90, 0.06/0.12 and 0.12/1 μg/mL, respectively). Susceptibility of ESBL screen-positive E. coli and K. pneumoniae was 100.0/97.9% for tigecycline and 99.2/56.1% for meropenem, respectively. Susceptibility to other agents for ESBL screen-positive E. coli and K. pneumoniae was decreased. Ceftaroline-avibactam exhibited a broad-spectrum of in vitro activity against isolates from patients in the USA with ABSSSI including MRSA, β-hemolytic streptococci, E. coli, and K. pneumoniae as well as ESBL screen-positive phenotype isolates and merits further study in clinical indications where these resistant organisms may be a concern.