title: Mechanisms of carbapenem resistance in cephalosporin-susceptible Pseudomonas aeruginosa in China.
abstract: Twenty-nine Pseudomonas aeruginosa isolates, which are resistant to carbapenems but susceptible to ceftazidime or/and cefepime, were recovered from our hospital from July 2011 to October 2011. The results of Western blotting showed that the OprD was reduced or lost. None of the 29 clinical isolates produced carbapenemases, extended-spectrum β-lactamases, or Ambler class C β-lactamases enzymes by the modified 3-dimensional test. The sequencing of oprD for these isolates showed that there are multiple point mutations, large fragment substitutions, deletions, and insertions. It showed that the expression of oprD decreased while mexA and mexX increased by real-time reverse transcriptase-PCR. These results suggested that the loss of OprD and overexpression of mexXY-OprM and mexAB-OprM are associated with carbapenem resistance in cephalosporin-susceptible Pseudomonas aeruginosa.
authors.affiliation: Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
authors.forename: Zhang-Rui
authors.initials: ZR
authors.lastname: Zeng
authors.affiliation: Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Wang
authors.affiliation: Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
authors.forename: Mei
authors.initials: M
authors.lastname: Huang
authors.affiliation: Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
authors.forename: Li-Ning
authors.initials: LN
authors.lastname: Shi
authors.affiliation: Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China. Electronic address: shf521201@163.com.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Shao
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins; D001483:Base Sequence; D015780:Carbapenems / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D002681:China; D004269:DNA, Bacterial / Q000302:isolation & purification; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D018272:Porins / Q000235:genetics* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D004269:DNA, Bacterial; D018272:Porins; C077157:OprD protein, Pseudomonas aeruginosa; D001618:beta-Lactamases; C063912:carbapenemase
keywords: Carbapenemases; Efflux pumps; OprD; Pseudomonas aeruginosa; Resistance mechanism