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Published on: May 8, 2013

Evaluation of phenotypic methods for methicillin resistance characterization in coagulase-negative staphylococci

Juliana Caierão1, Maiara Musskopf1, Silvana Superti1

  • 1Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Rua Sarmento Leite 245/211, Porto Alegre, RS 90050-170, Brazil 2Hospital Mãe de Deus, Porto Alegre, Brazil 3Laboratório Central de Análises Clínicas da Irmandade Santa Casa de Misericórdia de Porto Alegre, RS, Brazil.

Journal of Medical Microbiology
|December 9, 2004
PubMed

Insights

Detecting methicillin resistance in coagulase-negative staphylococci (CNS) is crucial for treating hospital infections. Agar screening with 4 microg oxacillin ml(-1) proved the most accurate method for identifying these resistant strains.

Area of Science:

  • Clinical Microbiology
  • Infectious Diseases
  • Antimicrobial Resistance

Background:

  • Coagulase-negative staphylococci (CNS) are a significant cause of hospital-acquired infections.
  • Methicillin resistance in CNS complicates treatment due to limited therapeutic choices.
  • Accurate detection of methicillin resistance in CNS is essential for effective patient management.

Purpose of the Study:

  • To evaluate the accuracy of different methods for detecting methicillin resistance in CNS.
  • To compare agar screening tests (0.6 and 4 microg oxacillin ml(-1)), disc diffusion, and the MicroScan system.
  • To identify the most reliable method for characterizing methicillin resistance among various CNS species.

Main Methods:

  • Analysis of 175 CNS strains, including Staphylococcus epidermidis and other species.
  • Detection of methicillin resistance using agar screening (0.6 and 4 microg oxacillin ml(-1)), disc diffusion, and the MicroScan automated system.
  • Correlation of test results with the presence of the mecA gene.

Main Results:

  • The mecA gene was detected in 69.1% of the analyzed CNS strains.
  • Agar screening, disc diffusion, and MicroScan showed optimal correlation with mecA detection for common species like S. epidermidis.
  • Test accuracy decreased for less common CNS species.
  • Agar screening at 4 microg oxacillin ml(-1) demonstrated 100% accuracy.

Conclusions:

  • Agar screening with 4 microg oxacillin ml(-1) is the most accurate method for detecting methicillin resistance in CNS.
  • Current detection methods may require adjustments for less common CNS species.
  • Accurate identification of methicillin-resistant CNS is vital for guiding antimicrobial therapy and infection control.

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