Vancomycin-resistant enterococci at a large university hospital in Denmark

Enterococci are part of the normal human fecal flora and also part of the fecal flora of many animals. Vancomycin- and ampicillin-resistant enterococci give rise to infections that may virtually be untreatable with antibiotics. Antibiotic use in humans is a risk factor for development or selection of vancomycin-resistant enterococci. In animals the related glycopeptide avoparcin is used, especially in poultry, as a food additive to promote growth. Selective pressures for vancomycin-resistant enterococci are high in Denmark with the production of 105 million poultry and the use of 24,000 kg avoparcin per year. The possible impact on vancomycin resistance among human isolates of enterococci remains to be defined. Furthermore, there has been a 3-fold increase in vancomycin usage during the last 5 years at our hospital, from 2.4 to 7 kg/year. We examined 91 stool specimens from 67 patients in risk units at our hospital. Using a selective medium (KAA agar), 17 strains of Enterococcus faecium grew on the selective medium and 3 (18%) were vancomycin-resistant (MIC > 256 mg/l). Using PCR and an internal probe, vanA was found in the vancomycin-resistant enterococci. No association between vancomycin therapy and carriage of VRE was demonstrated in these patients.