title: Molecular characterization of carbapenemase-producing clinical isolates of Enterobacteriaceae in a teaching hospital, Japan.
abstract: We examined the molecular characteristics of 13 phenotypically confirmed carbapenemase-positive Enterobacteriaceae clinical isolates, including the relationships between plasmid-mediated quinolone-resistance genes (qnr), 6'-N-aminoglycoside acetyltransferase-encoding genes [aac(6')] and AmpC-encoding genes (pAmpC). Twelve isolates were bla(IMP-1) positive (92.3%), while one was bla(IMP-11) positive (7.7%). We detected qnr, aac(6') and pAmpC genes designated bla(ACT-1)-like in 76.9%, 100% and 53.8%, respectively, of the 13 isolates. Plasmids were transferred successfully for three of the 13 metallo-β-lactamase (MBL)-producing isolates, and the sizes of plasmids extracted from these donors and transconjugants were deduced to be 65 kb or 70 kb. OmpC or OmpF protein expression was reduced in all Enterobacter cloacae, and one Klebsiella oxytoca lacked OmpK36. We demonstrate what appears to be the first evidence that, in Japan, Enterobacteriaceae producing MBLs carry various plasmid-mediated resistance genes, which may cause a further decrease in carbapenem susceptibility through reduction of the expression of outer-membrane proteins.
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.|Department of Infection Control and Prevention, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Saho
authors.initials: S
authors.lastname: Koyano
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Saito
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.|Department of Infection Control and Prevention, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Ran
authors.initials: R
authors.lastname: Nagai
authors.affiliation: Department of Infection Control and Prevention, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Tatsuno
authors.affiliation: Department of Infection Control and Prevention, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Okugawa
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Okamura
authors.affiliation: Department of Infection Control and Prevention, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Kyoji
authors.initials: K
authors.lastname: Moriya
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006784:Hospitals, Teaching; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001618:beta-Lactamases; C063912:carbapenemase