Open AccessAAC(6′)-Iaf, a Novel Aminoglycoside 6′- N -Acetyltransferase from Multidrug-Resistant Pseudomonas aeruginosa Clinical Isolates
Author(s) -
Tomoe Kitao,
Tohru MiyoshiAkiyama,
Teruo Kirikae
Publication year - 2009
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.01360-08
Subject(s) - integron , kanamycin , microbiology and biotechnology , amikacin , pseudomonas aeruginosa , aminoglycoside , biology , gentamicin , multiple drug resistance , neomycin , plasmid , antibiotics , antibiotic resistance , gene , bacteria , genetics
We report here the characterization of a novel aminoglycoside resistance gene,aac(6 ′)-Iaf , present in two multidrug-resistant (MDR)Pseudomonas aeruginosa clinical isolates. These isolates, IMCJ798 and IMCJ799, were independently obtained from two patients, one with a urinary tract infection and the other with a decubitus ulcer, in a hospital located in the western part of Japan. Although the antibiotic resistance profiles of IMCJ798 and IMCJ799 were similar to that of MDRP. aeruginosa IMCJ2.S1, which caused outbreaks in the eastern part of Japan, the pulsed-field gel electrophoresis patterns for these isolates were different from that for IMCJ2.S1. Both IMCJ798 and IMCJ799 were found to contain a novel chromosomal class 1 integron, In123, which includedaac(6 ′)-Iaf as the first cassette gene. The encoded protein, AAC(6′)-Iaf, was found to consist of 183 amino acids, with 91 and 87% identity to AAC(6′)-Iq and AAC(6′)-Im, respectively. IMCJ798, IMCJ799, andEscherichia coli transformants carrying a plasmid containing theaac(6 ′)-Iaf gene and its upstream region were highly resistant to amikacin, dibekacin, and kanamycin but not to gentamicin. The production of AAC(6′)-Iaf in these strains was confirmed by Western blot analysis. Thin-layer chromatography indicated that AAC(6′)-Iaf is a functional acetyltransferase that specifically modifies the amino groups at the 6′ positions of aminoglycosides. Collectively, these findings indicate that AAC(6′)-Iaf contributes to aminoglycoside resistance.