title: Increased prevalence and clonal dissemination of multidrug-resistant Pseudomonas aeruginosa with the blaIMP-1 gene cassette in Hiroshima.
abstract: OBJECTIVE
  The aim of this study was to evaluate the dissemination of metallo-beta-lactamase (MBL)-encoding genes among multidrug-resistant (MDR) Pseudomonas aeruginosa isolates recovered from major hospitals in the Hiroshima region.
  
  
  METHODS
  During July to December from 2004 to 2006, a surveillance of eight major hospitals in the Hiroshima region identified 387 non-duplicate isolates resistant to imipenem (MIC >or= 16 mg/L). They were screened for resistance to amikacin (MIC >or= 64 mg/L) and ciprofloxacin (MIC >or= 4 mg/L) and MBL-encoding genes. The structure of the variable regions of the integrons was determined using PCR mapping. Clonality was assessed using PFGE and multilocus sequence typing (MLST).
  
  
  RESULTS
  The frequency of MBL-positive isolates in MDR P. aeruginosa isolates significantly increased from 42.3% in 2004 to 81.4% in 2006. Most of the MBL-positive isolates produced IMP-1 followed by VIM-2. The bla(IMP-1) and bla(VIM-2) genes were present in class 1 integrons. Characterization of the variable regions of the integron showed the presence of six different gene cassette arrays in bla(IMP-1) cassettes and a single array in bla(VIM-2) cassettes. The IMP-1 producers belonged to two clonal lineages using PFGE and MLST analyses and the integron variations correlated well with the clonal complexes. Among them, strains positive for a newly identified In113-derived bla(IMP-1) gene cassette array were most widely distributed in Hiroshima.
  
  
  CONCLUSIONS
  This study shows a dramatic increase in MBL genes, primarily bla(IMP-1), in MDR P. aeruginosa isolates in Hiroshima during these 3 years. In addition, MDR P. aeruginosa with the newly discovered In113-derived bla(IMP-1) gene cassette array appears to be clonally expanding.
authors.affiliation: Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Syuntaro
authors.initials: S
authors.lastname: Kouda
authors.forename: Masaru
authors.initials: M
authors.lastname: Ohara
authors.forename: Makoto
authors.initials: M
authors.lastname: Onodera
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujiue
authors.forename: Megumi
authors.initials: M
authors.lastname: Sasaki
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Kohara
authors.forename: Seiya
authors.initials: S
authors.lastname: Kashiyama
authors.forename: Shizue
authors.initials: S
authors.lastname: Hayashida
authors.forename: Toshie
authors.initials: T
authors.lastname: Harino
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuji
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Itaha
authors.forename: Naomasa
authors.initials: N
authors.lastname: Gotoh
authors.forename: Akio
authors.initials: A
authors.lastname: Matsubara
authors.forename: Tsuguru
authors.initials: T
authors.lastname: Usui
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Sugai
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D005838:Genotype; D006761:Hospitals; D006801:Humans; D032023:Integrons; D007564:Japan / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D011552:Pseudomonas Infections / Q000453:epidemiology* / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000145:classification* / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; C409201:beta-lactamase IMP-1; D001618:beta-Lactamases