Volume 7, Number 2—April 2001
THEME ISSUE
4th Decennial International Conference on Nosocomial and Healthcare-Associated Infections
State of the Art
Increasing Resistance to Vancomycin and Other Glycopeptides in Staphylococcus aureus
Table 2
Key techniques for recognizing glycopeptide-intermediate Staphylococcus aureus strainsa
| Technique | Results | Comment |
|---|---|---|
| Broth microdilutionb | Vancomycin MIC = 8-16 µg/mL in Mueller-Hinton broth | Hold test for full 24 hours |
| Brain heart infusion agar containing 6 µg/mL of vancomycin obtained from a commercial sourcec | Growth in 24 hours | One or more colonies is a positive result; use S. aureus ATCC 25923 as negative control, and Enterococcus faecalis ATCC51299 as positive control |
| Etest | Vancomycin MIC > 6 µg/mL on Mueller-Hinton agar | Hold test for full 24 hour |
aAll three criteria must be met before an organism is defined as a glycopeptide-intermediate S. aureus. bCDC uses inhouse-prepared MIC plates; however, any full dilution range broth microdilution plates, such as MicroScan conventional panels or PASCO frozen MIC panels, if incubated at 35C for a full 24 hours, can be used. cSee reference 34 for explanation.
