Based on the results of the gram stain, catalase, PYR, and LAP tests, should this culture be reported as positive for VRE?
This culture cannot be reported as VRE at this point. The tests identify the isolate as Enterococcus species, but do not confirm that it is vancomycin resistant. This may be an isolate of Enterococcus gallinarum or Enterococcus casseliflavus, both of which show inherent, low-level resistance to vancomycin. Both can grow on the BEA screening medium. However, it is the high-level resistance to vancomycin, which occurs primarily in Enterococcus faecium and E. faecalis, and not organisms with intrinsic resistance, that are of interest to the infection control practitioners. Thus, additional testing must be performed to confirm acquired vancomycin resistance. Question: What can be done to differentiate isolates with intrinsic versus acquired vancomycin resistance? Answer: First, a vancomycin MIC test should be used to confirm that the organism is vancomycin resistant. Testing for ampicillin resistance simultaneously using MIC or disk diffusion can also be useful since ampicillin resistant s
