Detection of the High-Level Aminoglycoside Resistance Gene aph(2")-Ib in Enterococcus faecium

A new high-level gentamicin resistance gene, designated aph(2")-Ib, was cloned from Enterococcus faecium SF11770. The deduced amino acid sequence of the 897-bp open reading frame of aph(2")-Ib shares homology with the aminoglycoside-modifying enzymes AAC(6′)-APH(2"), APH(2")-Ic, and APH(2")-Id. The observed phosphotransferase activity is designated APH(2")-Ib.