First report of novel genetic array aacA4-blaIMP-25-oxa30-catB3 and identification of novel metallo-β-lactamase gene blaIMP25: A Retrospective Study of antibiotic resistance surveillance on Psuedomonas aeruginosa in Guangzhou of South China, 2003-2007.

Carbapenem, imipenem and meropenem have been broadly prescribed contributing to the global occurrence and prevalence of carbapenem resistance in Psuedomonas aeruginosa, and the associated resistance genotypes remains clinically significant. A retrospective surveillance had been conducted on 499 P. aeruginosa isolates in South China during 2003-2007, including antimicrobial resistance and characterization of MBLs on carbapenem-resistant strains. One hundred and sixty-four out of 499 strains were carbapenem-resistant, with 11, 4 and 5 strains positive for blaIMP-9, blaIMP-25 and blaVIM-2, respectively. Sixteen out of 20 isolates were positive for intI1 and contained identical flanking regions (as indicated in KM384735), and all tested isolates containing the qacE△1-sul1 of the typical 3'-conserved region. A novel blaIMP-25 metallo-β-lactamase and a genetic array of aacA4-blaIMP-25-oxa30-catB3 have been discovered from this retrospective surveillance on antimicrobial resistance of P. aeruginosa.