title: Carbapenem and cefoxitin resistance of Klebsiella pneumoniae strains associated with porin OmpK36 loss and DHA-1 β-lactamase production.
abstract: Clinical isolates of carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) strains are being increased worldwide. Five pan-resistant K. pneumoniae strains have been isolated from respiratory and ICU wards in a Chinese hospital, and reveal strong resistance to all β-lactams, fluoroquinolones and aminoglycosides. Totally 27 β-lactamase genes and 2 membrane pore protein (porin) genes in 5 K. pneumoniae strains were screened by polymerase chain reaction (PCR). The results indicated that all of 5 K. pneumoniae strains carried blaTEM-1 and blaDHA-1 genes, as well as base deletion and mutation of OmpK35 or OmpK36 genes. Compared with carbapenem-sensitive isolates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the resistant isolates markedly lacked the protein band of 34-40 kDa, which might be the outer membrane proteins of OmpK36 according to the electrophoresis mobility. In addition, the conjugation test was confirmed that blaDHA-1 mediated by plasmids could be transferred between resistant and sensitive strains. When reserpine (30 μg/mL) and carbonyl cyanide m-chlorophenylhydrazone (CCCP) (50 μg/mL) were added in imipenem and meropenem, the MICs had no change against K. pneumoniae strains. These results suggest that both DHA-1 β-lactamase and loss or deficiency of porin OmpK36 may be the main reason for the cefoxitin and carbapenem resistance in K. pneumoniae strains in our hospital.
authors.affiliation: Department of Clinical Laboratory, Third Affiliated Hospital of Suzhou University, Changzhou, P.R. China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Shi
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Ji
authors.forename: Qinbo
authors.initials: Q
authors.lastname: Jiang
authors.forename: Yuyue
authors.initials: Y
authors.lastname: Wang
authors.forename: Mei
authors.initials: M
authors.lastname: Shi
authors.forename: Zuhuang
authors.initials: Z
authors.lastname: Mi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000032:analysis; D015780:Carbapenems / Q000494:pharmacology*; D002440:Cefoxitin / Q000494:pharmacology*; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D006761:Hospitals; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000737:chemistry / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D018272:Porins / Q000172:deficiency*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D004269:DNA, Bacterial; C092233:OmpK36 protein, Klebsiella pneumoniae; D018272:Porins; D002440:Cefoxitin; D001618:beta-Lactamases
keywords: AmpC β-Lactamase; Klebsiella pneumoniae; Porin; molecular biology