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Published on: May 8, 2013

Glycopeptide minimum inhibitory concentration creep among meticillin-resistant Staphylococcus aureus from 2006-2011

Chao Zhuo1, Ying-chun Xu, Shu-nian Xiao

  • 1State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical College, Guangzhou, China. chao_sheep@263.net

International Journal of Antimicrobial Agents
|April 9, 2013
PubMed

Insights

Vancomycin resistance in MRSA is increasing in China, with higher minimum inhibitory concentrations (MICs) observed over time. This trend suggests a growing challenge in treating MRSA infections with standard glycopeptide antibiotics.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Clinical Pharmacy

Background:

  • Vancomycin minimum inhibitory concentration (MIC) creep, indicating reduced susceptibility, is a global concern for methicillin-resistant Staphylococcus aureus (MRSA).
  • Data on vancomycin MIC creep in China has been limited, necessitating local surveillance.

Purpose of the Study:

  • To investigate the trends in vancomycin, teicoplanin, and linezolid MICs among MRSA isolates in China from 2006 to 2011.
  • To evaluate the emergence of vancomycin MIC creep and assess susceptibility patterns to other antibiotics.

Main Methods:

  • Analysis of 1411 MRSA isolates collected from six Chinese hospitals between 2006 and 2011.
  • Determination of vancomycin, teicoplanin, and linezolid MICs using broth microdilution according to CLSI guidelines.
  • Calculation of MIC50, MIC90, and geometric mean (GM) MICs annually to evaluate MIC creep.

Main Results:

  • A statistically significant increasing trend in vancomycin GM MICs was observed (P<0.001), with values rising from 0.906 mg/L in 2006 to 1.040 mg/L in 2011.
  • The percentage of MRSA isolates with vancomycin MICs above 1 μg/mL increased significantly over the study period (P<0.005).
  • Teicoplanin GM MICs also showed a rapid increase, and approximately 5% of isolates were resistant according to EUCAST criteria, while linezolid MICs remained stable.

Conclusions:

  • A clear tendency towards decreasing susceptibility to glycopeptides, including vancomycin and teicoplanin, has emerged in Chinese MRSA isolates.
  • The observed vancomycin MIC creep highlights a potential challenge for effective MRSA treatment in China.
  • Continued monitoring of antimicrobial susceptibility is crucial for guiding clinical practice and infection control strategies.

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