en
Scientific article
English

Comparative activity of oritavancin against meticillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates from Geneva University Hospital

Published inInternational journal of antimicrobial agents, vol. 34, no. 6, p. 540-543
Publication date2009
Abstract

In this study, we assessed by broth microdilution the in vitro activity of oritavancin, a semisynthetic lipoglycopeptide currently under development, against selected meticillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates (n=56) from Geneva University Hospital, Switzerland, displaying a wide range of vancomycin minimum inhibitory concentrations (MICs) (0.25-4 microg/mL). The MRSA resistance phenotype was confirmed by broth microdilution (oxacillin MIC > or = 4 microg/mL) for all isolates; 89% and 100% of the tested isolates were also resistant to erythromycin and ciprofloxacin, respectively. For 53 MRSA isolates for which vancomycin MICs were in the susceptible range (0.5-2.0 microg/mL), the oritavancin MICs ranged from 0.03 microg/mL to 0.5 microg/mL. For these 53 vancomycin-susceptible isolates, the cumulative distribution of oritavancin MICs was markedly different from those of vancomycin, teicoplanin, daptomycin and linezolid MICs, yielding an oritavancin MIC for 90% of the organisms (MIC(90)) (0.25 microg/mL) that was four times lower than the MIC(90) values (1 microg/mL) of comparators. For three MRSA isolates with a vancomycin-intermediate phenotype (vancomycin MIC=4 microg/mL), oritavancin MICs (0.5-1.0 microg/mL) were 2-4-fold lower than vancomycin, teicoplanin or daptomycin MICs, but were equivalent to linezolid MICs. Pairwise comparison for each bloodstream isolate showed that oritavancin was > or =4-fold more active than vancomycin, teicoplanin and daptomycin, against 86%, 75% and 59% of all MRSA isolates, respectively.

Keywords
  • Anti-Bacterial Agents/ pharmacology
  • Bacteremia/ microbiology
  • Ciprofloxacin/pharmacology
  • Erythromycin/pharmacology
  • Glycopeptides/ pharmacology
  • Hospitals, Teaching
  • Humans
  • Methicillin-Resistant Staphylococcus aureus/ drug effects/isolation &
  • Purification
  • Microbial Sensitivity Tests
  • Staphylococcal Infections/ microbiology
  • Switzerland
  • Vancomycin/pharmacology
Citation (ISO format)
VAUDAUX, Pierre et al. Comparative activity of oritavancin against meticillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates from Geneva University Hospital. In: International journal of antimicrobial agents, 2009, vol. 34, n° 6, p. 540–543. doi: 10.1016/j.ijantimicag.2009.07.016
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ISSN of the journal0924-8579
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