M. Kawalec

, J. Ke¸dzierska, A. Gajda, E. Sadowy, J. We¸grzyn, S. M. Naser, A. B. Skotnicki ,M. Gniadkowski and W. Hryniewicz

A mixed outbreak caused by vancomycin-resistant

Enterococcus raffinosus and Enterococcus faecium

vanA gene was analysed. The outbreak occurred in a large hospital in Poland and affected

27 patients, most of whom were colonised, in three wards, including the haematology unit. The

isolates had a high-level multiresistant phenotype and were initially misidentified as

; their unambiguous identification was provided by multilocus sequence analysis. The

molecular investigation demonstrated the clonal character of the

E. raffinosus outbreak and the

polyclonal structure of the

E. faecium isolates. All of the isolates carried the same Tn1546-like element

containing an IS

1251-like insertion sequence, located on a c. 50-kb conjugative plasmid. One of the

clones, found previously to be endemic in the hospital, was probably the source of the

plasmid. The results of the study suggest that difficulties in identification may have led to an

E. raffinosus in vancomycin-resistant enterococci (VRE) control

strategies.