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

NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

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.