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.

CSTE Position Statement(s)

  • 09-ID-58
  • 09-ID-59

Clinical Description

Staphylococcus aureus can produce a variety of syndromes with clinical manifestations including skin and soft tissue infections, empyema, bloodstream infection, pneumonia, osteomyelitis, septic arthritis, endocarditis, sepsis, and meningitis. S. aureus may also colonize individuals who remain asymptomatic. The most frequent site of S. aureus colonization is the nares.

Laboratory Criteria For Diagnosis

  • Isolation of S. aureus from any body site, AND
  • Intermediate or resistance of the S. aureus isolate to vancomycin, detected and defined according to Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) approved standards and recommendations (Minimum Inhibitory Concentration [MIC]=4-8 µg/ml for VISA and MIC≥16 µg/ml for VRSA).

Case Classification


A case of vancomycin-intermediate or vancomycin-resistant S. aureus that is laboratory-confirmed (MIC=4-8 µg/ml for VISA and MIC≥16 µg/ml for VRSA).


The 2007 case definition appearing on this page was re-published in the 2009 CSTE position statement 09-ID-58 and 09-ID-59. Thus, the 2007 and 2010 versions of the case definition are identical.


  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.
  3. Clinical and Laboratory Standards Institute/NCCLS. Performance Standards for Antimicrobial Susceptibility Testing. Sixteenth informational supplement. M100-S16. Wayne, PA: CLSI, 2006.

Related Case Definition(s)

Page last reviewed: April 16, 2021