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Activity of ceftaroline against selected clinical isolates of Staphylococcus aureus from the Canadian Bacterial Sentinel Network

Abstract number: P938

Objective: To evaluate the activities of ceftaroline against contemporary clinical isolates of Staphylococcus aureus collected in Canadian medical centres as part of the Canadian Bacterial Surveillance Network (CBSN). Ceftaroline is a novel, parenteral cephalosporin exhibiting bactericidal activity against Gram-positive organisms, including methicillin-susceptible and -resistant S. aureus (MSSA and MRSA), and common Gram-negative pathogens. CBSN has conducted cross-Canada S. aureus surveillance since 1987.

Methods: Susceptibility testing for ceftaroline and comparator antimicrobials was performed using CLSI broth microdilution methods on 591 isolates obtained from the CBSN (1999–2009) supplemented with 42 strains from the Network of Antimicrobial Resistance in S. aureus (NARSA) program. Community-acquired (CA) and hospital-acquired (HA) MRSA, MSSA, and vancomycin-intermediate S. aureus (VISA) isolates were included. Where possible, the most recent CBSN isolates were selected; number of isolates per year (year/n): 1999/1; 2002/92; 2003/62; 2004/40; 2005/56; 2006/25; 2007/195; 2008/110; 2009/10.

Results: Ceftaroline exhibited activity against all 633 strains and all MRSA, MSSA, and VISA subgroups (highest ceftaroline MIC, 2 mg/L) (Table). Ceftaroline had a lower MIC90 against MSSA strains (n = 105; MIC90, 0.25 mg/L) than against MRSA strains (n = 528, MIC90, 1 mg/L). Resistance to mupirocin, tetracycline, gentamicin, fusidic acid, erythromycin, or cotrimoxazole, and decreased susceptibility to vancomycin, did not affect ceftaroline activity against S. aureus.

Conclusions: Ceftaroline demonstrated potent in vitro activity against selected contemporary CBSN and NARSA S. aureus isolates, including strains with resistance to methicillin and/or reduced susceptibility to vancomycin. S. aureus resistance to commonly used antimicrobials did not adversely affect ceftaroline activity. These data highlight the potential utility of ceftaroline in treating S. aureus infections, including MSSA, MRSA, and VISA, in both community and hospital settings.

 nCumulative % at ceftaroline MIC
(mg/L)
MIC
(mg/L)
  0.120.250.512MIC50MIC90
All6332.117.975.895.11000.51
CA-MRSA214-1.889.799.51000.51
CA-MSSA861498.8100--0.250.25
HA-MRSA275-2.260.490.21000.51
HA-MSSA147.185.7100--0.250.25
MR-VISA39-2.643.692.310011
MS-VISA5-100-----
MR = methicillin resistant; MS = methicillin susceptible.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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