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Clinical relevance of increasing glycopeptide MICs against Staphylococcus aureus

Ian M Gould1

  • 1Department of Medical Microbiology, Aberdeen Royal Infirmary, Foresterhill, Aberdeen, UK.

International Journal of Antimicrobial Agents
|May 20, 2008
PubMed

Insights

Glycopeptide antibiotics are crucial for treating Gram-positive bacterial infections, but rising minimum inhibitory concentrations (MICs) in Staphylococcus aureus strains, including MRSA, are concerning. Continuous MIC surveillance is vital for effective empiric therapy selection.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Glycopeptides, including vancomycin, are frontline treatments for Gram-positive bacterial infections, particularly methicillin-resistant Staphylococcus aureus (MRSA).
  • Concerns exist regarding glycopeptide efficacy against MRSA due to poor tissue penetration, slow bacterial killing, and increasing resistance.
  • Glycopeptide creep, characterized by incremental increases in MICs for S. aureus, has been observed in single-center studies.

Purpose of the Study:

  • To highlight the growing challenge of glycopeptide resistance in Staphylococcus aureus.
  • To emphasize the clinical implications of increasing minimum inhibitory concentrations (MICs) for glycopeptides.
  • To advocate for accurate MIC measurement and surveillance in clinical practice.

Main Methods:

  • Review of existing literature on glycopeptide susceptibility trends in Staphylococcus aureus.
  • Analysis of the correlation between elevated MICs and clinical outcomes.
  • Discussion of the phenomenon of glycopeptide creep.

Main Results:

  • Single-center studies indicate a trend of increasing glycopeptide MICs for S. aureus over time (glycopeptide creep).
  • Elevated MICs, even below established susceptibility breakpoints, are associated with reduced clinical efficacy.
  • Poor tissue penetration and slow bactericidal activity of glycopeptides contribute to treatment challenges.

Conclusions:

  • Accurate and ongoing surveillance of glycopeptide MICs is essential for effective treatment of serious S. aureus infections.
  • Clinicians should be aware of potential decreases in glycopeptide susceptibility when selecting empiric therapy.
  • Monitoring MIC trends can guide therapeutic choices and antimicrobial stewardship efforts.

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