Detection of clinical vancomycin-resistant enterococci in Denmark by multiplex PCR and sandwich hybridization

Since the first cases of human infection with vancomycin-resistant enteroco cci (VRE) were reported in the late eighties, there has been a dramatic inc rease in VRE all over the world. So far, there have not been any reports of clinical VRE in Denmark. In this study we have investigated 131 clinically important enterococci sent to Statens Serum Institut from all over Denmark during the period July 1995 to May 1997. The susceptibility to vancomycin, teicoplanin, ampicillin and gentamicin was tested by the agar dilution met hod. In addition, two methods were developed to detect the different genoty pes of glycopeptide resistance described in enterococci: a multiplex PCR as say for detection of vanA, vanB, vanC-1, vanC-2/3 ligase genes including 16 S rRNA gene control primers and a sandwich hybridization assay to confirm v anA and vanB PCR-positive strains. The highest frequency of resistance to t he tested antibiotics was found in the Enterococcus faecium group. Four str ains were found with acquired resistance to glycopeptides: one E. faecium a nd one E. gallinarum were vanA positive, and two E. faecium isolates were v anB positive. These strains were isolated from different hospitals in diffe rent periods of time, and all patients recovered from their infections with VRE. Today, the PCR and sandwich hybridization methods are used for screen ing of vancomycin-resistant enterococci in humans as part of the Danish sur veillance programme.