Multidrug-Resistant Pseudomonas aeruginosa Strain That Caused an Outbreak in a Neurosurgery Ward and Its aac(6′)-Iae Gene Cassette Encoding a Novel Aminoglycoside Acetyltransferase

Abstract

We characterized multidrug-resistant Pseudomonas aeruginosa strains isolated from patients involved in an outbreak of catheter-associated urinary tract infections that occurred in a neurosurgery ward of a hospital in Sendai, Japan. Pulsed-field gel electrophoresis of SpeI-, XbaI-, or HpaI-digested genomic DNAs from the isolates revealed that clonal expansion of a P. aeruginosa strain designated IMCJ2.S1 had occurred in the ward. This strain possessed broad-spectrum resistance to aminoglycosides, ␤-lactams, fluoroquinolones, tetracyclines, sulfonamides, and chlorhexidine. Strain IMCJ2.S1 showed a level of resistance to some kinds of disinfectants similar to that of a control strain of P. aeruginosa, ATCC 27853. IMCJ2.S1 contained a novel class 1 integron, In113, in the chromosome but not on a plasmid. In113 contains an array of three gene cassettes of bla IMP-1 , a novel aminoglycoside resistance gene, and the aadA1 gene. The aminoglycoside resistance gene, designated aac(6)-Iae, encoded a 183-amino-acid protein that shared 57.1% identity with AAC(6)-Iq. Recombinant AAC(6)-Iae protein showed aminoglycoside 6-N-acetyltransferase activity by thin-layer chromatography. Escherichia coli expressing exogenous aac(6)-Iae showed resistance to amikacin, dibekacin, isepamicin, kanamycin, netilmicin, sisomicin, and tobramycin but not to arbekacin, gentamicins, or streptomycin. Alterations of gyrA and parC at the amino acid sequence level were detected in IMCJ2.S1, suggesting that such mutations confer the resistance to fluoroquinolones observed for this strain. These results indicate that P. aeruginosa IMCJ2.S1 has developed multidrug resistance by acquiring resistance determinants, including a novel member of the aac(6)-I family and mutations in drug resistance genes.

Antimicrobial Resistance of <i>Pseudomonas aeruginosa</i> Isolated from Dogs and Cats in Primary Veterinary Hospitals in Japan

“…In contrast to the results of this study, MBL producers and MDRP strains have been found at considerably higher frequencies in previous studies of human isolates in Japan (3)(4)(5)9). Furthermore, IMP-45-producing P. aeruginosa of canine origin was isolated in China, suggestive of a human-to-dog transfer (15).…”

Primary mechanisms mediating aminoglycoside resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7

“…Recently, a multidrug-resistant P. aeruginosa carrying the aac(69)-Iae gene, namely IMCJ2.S1 (Sekiguchi et al, 2005), was shown to have caused an outbreak in Japanese (1) residues 228-237 are deleted causing a frame shift that results in a premature stop at codon TGA at the position 419-421, and (2) the T at position 255 (underlined) is changed to a C without altering the MexZ amino acid sequence. In addition, the start codon of mexZ in DSM 1128 seems to be GTG at the position 1-3 according to the mexZs of PAO1, PA14 etc.…”

“…A recombinant E. coli containing AAC(69)-Iae is resistant to amikacin and tobramycin, but not to gentamicin or arbekacin (Sekiguchi et al, 2005). We assessed the impact of mexXY genes on aminoglycoside resistance in IMCJ2.S1 (Table 1).…”

Complete Genome Sequence of Highly Multidrug-Resistant Pseudomonas aeruginosa NCGM2.S1, a Representative Strain of a Cluster Endemic to Japan

“…The MDR P. aeruginosa strain NCGM2.S1 caused an outbreak of urinary tract infection at a hospital in Miyagi Prefecture, northern Japan (6). NCGM2.S1 harbors a metallo-␤-lactamase gene, blaIMP-1, and an aminoglycoside 6Ј-N-acetyltransferase gene, aac(6Ј)-Iae, in the class I integron In113 (6). Epidemiological studies indicated that clonal expansion of NCGM2.S1 occurred in hospitals in this area (7) as well as other areas in Japan (4,8).…”

“…The emergence of multidrug-resistant (MDR) P. aeruginosa strains is a serious problem in Japan (2,6,7). The MDR P. aeruginosa strain NCGM2.S1 caused an outbreak of urinary tract infection at a hospital in Miyagi Prefecture, northern Japan (6).…”