Vancomycin Minimum Inhibitory Concentrations Against Staphylococcus aureus

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Some studies have associated higher minimum inhibitory concentrations (MICs) in Staphylococcus aureus with an increased likelihood of therapeutic failure. Infectious diseases consultation should considered for patients with severe infections due to Staph aureus with a vancomycin MIC of 2 or higher.  (Note: to date studies do not indicate a strong relationship between vancomycin MIC and outcomes in Staphylococcus epidermidis, where a vancomycin MIC of 2 is common). *2015 isolates are those only submitted from inpatient locations, not including Emergency Department.

Adult Inpatient Vancomycin MIC Distribution for S. aureus

Vancomycin MIC in mg/L (All S. aureus)

2012

2013

2014

2015*

0.5

1.86% (12/645)

2.7% (16/588)

1.6% (8/486)

1.1% (4/352)

1

92% (594/645)

91.2% (536/588)

89.9% (437/486)

91.2% (321/352)

2

5.74% (37/645)

5.6% (33/588)

8.4% (41/486)

7.7% (27/352)

4

0.31% (2/645)

0.34% (2/588)

0% (0/486)

0.16% (1/608)

Vancomycin MIC in mg/L (MRSA only)

       

0.5

0.72% (2/276)

1.2% (3/248)

0.6% (1/168)

0.7% (1/136)

1

92% (255/276)

88.7% (220/248)

86.3% (145/168)

84.5% (115/136)

2

6.2% (17/276)

9.3% (23/248)

13.1% (22/168)

14.7% (20/136)

4

0.72% (2/276)

0.8% (2/249)

0% (0/168)

0% (0/136)