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Vancomycin-intermediate Staphylococcus Aureus and Vancomycin-resistant Staphylococcus Aureus (VISA/VRSA)
2004 Case Definition

Clinical Description

Staphylococcus aureus can produce a variety of syndromes with clinical manifestations including skin and soft tissue lesions, empyema, pyarthrosis, bloodstream infection, pneumonia, osteomyelitis, septic arthritis, endocarditis, sepsis, and meningitis.

Laboratory Criteria for Diagnosis

  • Isolation of S. aureus from any body site. AND
  • Intermediate or high-level resistance of the S. aureus isolate to vancomycin, detected and defined according to NCCLS* approved standards and recommendations (MIC: 8-16 µg/ml for VISA and MIC:≥32 µg/ml for VRSA).

Case Classification


A clinically compatible case of vancomycin-intermediate or vancomycin-resistant S. aureus that is laboratory-confirmed (MIC: 8-16 µg/ml for VISA and MIC: ≥32 µg/ml for VRSA).


Data to be collected: A standardized data collection form should be used for all reported vancomycin-intermediate or vancomycin-resistant S. aureus through the National Notifiable Diseases Surveillance System.

* National Committee for Clinical Laboratory Standards


  1. NCCLS. (2003) Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; Approved standard 6th ed., vol. 23, No. 2. Approved standard M7-A5. NCCLS, Wayne, Pa.
  2. NCCLS. (2003) Performance standards for antimicrobial susceptibility testing; Thirteenth informational supplement M100-S13 (M7). NCCLS, Wayne, Pa.