Is vancomycin redundant for serious staphylococcal infection?

Area of Science:

• Clinical microbiology
• Pharmacology
• Infectious diseases

Background:

• Vancomycin use is increasing, leading to rising minimum inhibitory concentrations (MICs).
• Current vancomycin breakpoints (2 mg/L) lack clinical relevance.
• Lowering breakpoints to 0.5 or 1 mg/L risks laboratory misclassification and reduced reproducibility.

Purpose of the Study:

• To evaluate the clinical utility of vancomycin in light of rising MICs.
• To assess the optimal pharmacokinetic/pharmacodynamic (PK/PD) targets for vancomycin therapy.
• To explore strategies for preserving vancomycin's efficacy against resistant strains.

Main Methods:

• Analysis of clinical data and existing literature on vancomycin MICs and PK/PD targets.
• Evaluation of the impact of rising MICs on treatment outcomes.
• Assessment of vancomycin toxicity and its implications for dose escalation.

Main Results:

• Modal vancomycin MICs are frequently ≥1 mg/L, challenging current susceptibility breakpoints.
• The optimal target of area under the curve (AUC)/MIC ratio of 400 is supported by limited clinical data.
• Vancomycin toxicity may preclude dose escalation to achieve therapeutic targets.
• Elevated MICs correlate with other bacterial changes that reduce drug efficacy.

Conclusions:

• Vancomycin's effectiveness is threatened by increasing resistance.
• Reducing vancomycin use is crucial to mitigate further selective pressure.
• Teicoplanin efficacy may also be compromised by similar resistance mechanisms.