Structures, locations, and transfer frequencies of genetic elements conferring high-level gentamicin resistance in Enterococcus faecalis isolates in Greece.

The elements conferring high-level gentamicin resistance in 64 clinical isolates of Enterococcus faecalis were characterized by PCR and by restriction enzyme hybridization analysis of genomic and plasmid DNA. There was a strong association between gentamicin resistance and the aac(6′)-aph(2") gene carried on IS256-based elements with different structures, locations, and transfer characteristics.