P106 Comparing susceptibility profiles of antibiotics by contour interval analysis: Ceftaroline and Belgian Streptococcus pneumoniae (SP) and MRSA isolates

Abstract

Ceftaroline, the active metabolite of the prodrug ceftaroline fosamil, is a novel cephalosporin exhibiting bactericidal activity in vitro against Gram-positive organisms, including meticillin-susceptible Staphylococcus aureus (MSSA), meticillin-resistant S. aureus (MRSA), β-haemolytic streptococci, viridans group streptococci (VGS) and Streptococcus pneumoniae, as well as against many common Gram-negative organisms. The objective of this study was to determine the spectrum and potency of ceftaroline against recent (2010) leading pathogens causing complicated skin and soft-tissue infections (cSSTIs) isolated in Europe. A total of 2438 isolates from the Assessing Worldwide Antimicrobial Resistance and Evaluation (AWARE) programme were identified as cSSTI pathogens. Isolates were collected from patients in 52 medical centres in 19 European countries. Reference susceptibility testing for ceftaroline and commonly used antimicrobials was performed by broth microdilution methodologies. Ceftaroline was very active overall against S. aureus (MIC50/90 = 0.25/1 mg/L) and inhibited 100.0% of isolates at a MIC of ≤2 mg/L. Activity against MRSA was documented (MIC50/90 = 1/2 mg/L) but was lower than that observed against MSSA (MIC50/90 = 0.25/0.25 mg/L). Ceftaroline was also very active against 460 β-haemolytic streptococci and 93 VGS (MIC90 = 0.015 mg/L and 0.06 mg/L, respectively). Ceftaroline was active against Escherichia coli (MIC50 = 0.12 mg/L) and Klebsiella pneumoniae (MIC50 = 0.06 mg/L) not expressing extended-spectrum β-lactamases, with activity similar to ceftriaxone and ceftazidime. In summary, this study documents the potent in vitro activity of ceftaroline when tested against recent pathogens isolated from patients with cSSTI in Europe.