CHARACTERIZATION OF VANCOMYCIN RESISTANCE IN ENTEROCOCCUS DURANS

During investigation of an outbreak of vancomycin resistant Enterococcus faecium in a paediatric hospital, an isolate of Enterococcus durans resistant to vancomycin, teicoplanin, ampicillin and highly resistant to gentamicin and streptomycin was found in the stools of a patient also colonized with a strain of E. faecium with the same resistance pattern. Minimal inhibitory concentrations of vancomycin and teicoplanin were 512 and 64 mg/mL, respectively. Resistance to vancomycin as well as high-level resistance to gentamicin was transferable to an E. faecium recipient strain. Both multiresistant E.faecium and E. durans isolates as well as the transconjugant presented only one plasmid. The vanA gene was detected and localized to the high molecular weight plasmid by DNA hybridization with a vanA gene probe. Growth in vancomycin resulted in induction of an approximately 40 kDa protein visible in membrane preparations from these cells. Genetic linkage between vancomycin and gentamicin resistance genes in the same plasmid is suggested.