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In vitro activity of daptomycin and comparator agents against Staphylococcus aureus isolates from intravenous drug

Antonio Sanchez-Porto1, Manuel Casanova-Roman, Javier Casas-Ciria

  • 1Department of Microbiology, Hospital of La Línea, Cádiz, Spain.

Le Infezioni in Medicina
|July 9, 2010
PubMed

Insights

Daptomycin and linezolid show promise as effective treatments for Staphylococcus aureus endocarditis, including strains resistant to vancomycin. These antibiotics offer viable alternatives for patients with right-sided endocarditis and bloodstream infections.

Area of Science:

  • Infectious Diseases
  • Antimicrobial Resistance
  • Clinical Microbiology

Background:

  • Rising incidence of vancomycin-intermediate Staphylococcus aureus (VISA) necessitates alternative endocarditis treatments.
  • Staphylococcus aureus is a common cause of infective endocarditis, particularly in intravenous drug users.
  • Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant therapeutic challenge.

Purpose of the Study:

  • To evaluate the in vitro activity of daptomycin and comparator agents against clinical isolates of Staphylococcus aureus from patients with right-sided endocarditis.
  • To assess daptomycin's efficacy in comparison to other antibiotics, particularly against vancomycin-intermediate strains.

Main Methods:

  • In vitro susceptibility testing of 33 clinical Staphylococcus aureus isolates (30 MSSA, 3 MRSA) using wider microdilution panels and E-test strips.
  • Determination of minimum inhibitory concentrations (MICs) for daptomycin, vancomycin, and linezolid.
  • Screening of MRSA isolates with elevated vancomycin MICs using E-test GRD for vancomycin intermediate resistance.

Main Results:

  • Daptomycin demonstrated potent in vitro activity with a MIC90 of 0.25 µg/mL against all tested Staphylococcus aureus isolates.
  • Linezolid also showed good activity with a MIC90 of 2 µg/mL.
  • Daptomycin and vancomycin MICs determined by wider microdilution panels and E-test strips were consistent.

Conclusions:

  • Daptomycin and linezolid are effective alternatives for treating right-sided endocarditis and bacteremia caused by methicillin-susceptible (MSSA), methicillin-resistant (MRSA), and vancomycin-intermediate (hVISA) Staphylococcus aureus.
  • These agents provide crucial therapeutic options in the face of increasing antimicrobial resistance.

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