The Food and Drug Administration (FDA) has lowered the breakpoints for vancomycin in the treatment of Staphylococcus aureus to reflect growing rates of resistance, and in response to urging from IDSA and others. 

According to a recently updated package insert for Baxter Healthcare Corporation’s vancomycin injection in GALAXY plastic containers, the susceptibility test interpretive criteria for S. aureus have been changed as follows:

The breakpoints for other infections remain unchanged. 

(Note: see "High-Dose Vancomycin May Lead to Nephrotoxicity" in this issue's IDSA Literature Review.)

Clinicians are encouraged to make sure that clinical microbiology laboratories with which they are associated are using the revised vancomycin susceptibility breakpoints for S. aureus.  

The change follows mounting evidence that patients infected with S. aureus strains with MIC of 4 µg/mL were failing therapy.  Robert C. Moellering, Jr., MD, FIDSA, past president of IDSA, and Fred C. Tenover, PhD, FIDSA, published a “Viewpoints” article in the May 1, 2007 issue of Clinical Infectious Diseases detailing the rationale for lowering the breakpoints. The article was based on data Dr. Tenover had collected and presented to the Clinical and Laboratory Standards Institute (CLSI), which updated its breakpoints last year and submitted a “Citizens’ Petition” to FDA advising the agency to do the same. 

For years, IDSA has been urging FDA to update breakpoints for key antimicrobials and backed legislation passed last fall requiring the agency to do so. This is the second time in recent months that FDA has updated breakpoints for a major antibiotic and suggests a new willingness on the part of the agency to modify these important benchmarks. 

In related news, see the article in this issue of IDSA News on the recent FDA meeting to hear testimony on other key antimicrobial issues.

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