Novel 6′-N-Aminoglycoside Acetyltransferase AAC(6′)-Iaj from a Clinical Isolate of Pseudomonas aeruginosa

Abstract

ABSTRACTPseudomonas aeruginosaNCGM1588 has a novel chromosomal class 1 integron, In151, which includes theaac(6′)-Iajgene. The encoded protein, AAC(6′)-Iaj, was found to consist of 184 amino acids, with 70% identity to AAC(6′)-Ia.Escherichia colitransformed with a plasmid containing theaac(6′)-Iajgene acquired resistance to all aminoglycosides tested except gentamicin. Of note,aac(6′)-Iajcontributed to the resistance to arbekacin. Thin-layer chromatography revealed that AAC(6′)-Iaj acetylated all aminoglycosides tested except gentamicin. These findings indicated that AAC(6′)-Iaj is a functional acetyltransferase that modifies the amino groups at the 6′ positions of aminoglycosides and contributes to aminoglycoside resistance ofP. aeruginosaNCGM1588, including arbekacin.