Carbapenem susceptibility breakpoints, clinical implications with the moving target

Area of Science:

• Microbiology
• Infectious Diseases
• Clinical Pharmacy

Background:

• Carbapenems are essential for treating Gram-negative multi-drug resistant infections.
• Increasing carbapenem use has driven a rise in antimicrobial resistance, indicated by higher MICs.
• Antimicrobial susceptibility breakpoints are critical for guiding therapy.

Purpose of the Study:

• To review the rationale behind recent changes in carbapenem susceptibility breakpoints by regulatory bodies.
• To analyze the clinical outcomes for patients treated with carbapenems for infections with MICs near the breakpoint.
• To examine the pharmacokinetic and pharmacodynamic principles supporting these breakpoint adjustments.

Main Methods:

• Literature review focusing on studies examining carbapenem breakpoint changes.
• Analysis of clinical outcomes data related to carbapenem therapy and MIC values.
• Review of pharmacokinetic/pharmacodynamic (PK/PD) data relevant to carbapenem efficacy.

Main Results:

• Regulatory bodies (CLSI, FDA, EUCAST) have lowered carbapenem susceptibility breakpoints.
• These changes aim to better align susceptibility testing with achievable clinical outcomes.
• Understanding PK/PD is crucial for interpreting MICs and breakpoint implications.

Conclusions:

• Recent adjustments in carbapenem susceptibility breakpoints reflect evolving resistance patterns.
• Lowered breakpoints may impact treatment decisions and clinical outcomes for Gram-negative infections.
• Further research is needed to fully elucidate the clinical utility of revised breakpoints.