Molecular Characterization of the vanD Gene Cluster and a Novel Insertion Element in a Vancomycin-Resistant Enterococcus Isolated in Canada

A single vanD -containing Enterococcus faecium strain (N97-330) was isolated in Canada. The vanD -containing region was cloned and sequenced. Although the proteins have more than 96% identity to a previously described vanD region in BM4339, the vanS D gene contains a frameshift mutation that leads to a predicted truncated protein. Furthermore, sequence analysis of the ddl gene revealed the presence of an IS 982 -like element (IS Efm1 ) which interrupted the d -Ala– d -Ala ligase. This suggested the constitutive expression of the vanD operon, which was confirmed. Pulsed-field gel electrophoresis fingerprinting demonstrated that BM4339 was not related to N97-330 (>15 band differences). Both strains contained multiple copies of the IS 982 -like element.