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Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)
12:18

Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)

Published on: February 9, 2011

Pseudo-outbreak of methicillin-resistant Staphylococcus aureus

P T Ender1, S J Durning, W K Woelk

  • 1Division of Infectious Diseases, Wright-Patterson Medical Center, Wright-Patterson AFB, Ohio 45433-5529, USA.

Mayo Clinic Proceedings
|September 17, 1999
PubMed
Abstract

Insights

Laboratory misclassification led to a high rate of methicillin-resistant Staphylococcus aureus (MRSA) detection. Most MRSA cases were false positives, causing unnecessary vancomycin use and infection control measures.

Area of Science:

  • Clinical Microbiology
  • Infectious Diseases
  • Diagnostic Accuracy

Background:

  • High rates of methicillin-resistant Staphylococcus aureus (MRSA) can strain healthcare resources.
  • Accurate laboratory identification of MRSA is crucial for effective treatment and infection control.

Purpose of the Study:

  • To investigate if laboratory misclassification contributed to the observed high rate of MRSA.
  • To assess the impact of potential misclassification on patient care and hospital protocols.

Main Methods:

  • Comparison of automated Vitek system results with oxacillin agar screen and broth microdilution.
  • Testing of discordant isolates for the presence of the mecA gene.
  • Evaluation of S. aureus isolates over a 60-day period.

Main Results:

  • 72% of isolates initially identified as MRSA by the Vitek system were oxacillin susceptible via agar screening.
  • Discordant isolates were confirmed as oxacillin susceptible and mecA gene negative.
  • Misclassification led to unnecessary vancomycin use and infection control measures.

Conclusions:

  • Automated susceptibility testing for S. aureus requires periodic validation.
  • Hospitals should implement confirmatory testing to prevent MRSA misclassification.
  • Accurate MRSA identification is vital to avoid resource misallocation.

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