title: [Isolation of a carbapenem-resistant K1 serotype Klebsiella pneumonia strain and the study of resistance mechanism].
abstract: OBJECTIVE
  To study the virulence and mechanism of carbapenem resistance of a clinical isolate of carbapenem-resistant K1 serotype Klebsiella pneumonia strain.
  
  
  METHODS
  Identification of isolate was carried out with VITEK-2 compact system. Antimicrobial susceptibility was determined by E-test; Metallo β-lactamases and carbapenemases screening were conducted by imipenem-EDTA double disc synergy test and modified Hodge test, respectively.Specific polymerehse chain reaction (PCR) and DNA sequencing were preformed to detect the virulence genes including K1, K2, K5, K20, K54, K57, magA, rmpA, wcaG and a series of β-lactamase resistence genes. Conjunction experiment was also performed. The plasmids of transconjugants were submitted to PCR-based replicon typing (PBRT) method. Molecular typing was performed by multilocus sequence typing (MLST).
  
  
  RESULTS
  Antimicrobial susceptibility testing revealed that the Klebsiella pneumonia strain was resistant to most of the antibiotics used in clinic. Phynotype confirmary rest revealed the production of carbapanemases, while Metallo β-lactamases were negative; PCR and DNA sequencing confirmed the isolate was positive for blaKPC-2, blaCTX-M-15, blaTEM-1, blaSHV-1 and virulence genes K1, magA, rmpA, wcaG simultaneously; blaKPC-2 was transferred from donor to Escherichia EC600 by conjunction experiment, while no virulence genes were found in the transconjugants. PBRT revealed that Frep plasmid was found in transconjugants. MLST analysis revealed that this strain belonged to ST23.
  
  
  CONCLUSIONS
  K1 serotype Klebsiella pneumonia strain carries virulence genes and carbapenem resistance gene blaKPC-2, noteworthily the carbapenem resistance genes can be transferred through horizontal transmission on plasmids.
authors.affiliation: School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Zhang
authors.affiliation: School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou 325035, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou 325035, China. Email: brigitte_zx@163.com.
authors.forename: Jianxin
authors.initials: J
authors.lastname: Lü
mesh_terms: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D024881:Drug Resistance, Bacterial; D006801:Humans; D007710:Klebsiella Infections; D007711:Klebsiella pneumoniae; D058885:Multilocus Sequence Typing; D010957:Plasmids; D011014:Pneumonia; D014774:Virulence; D001618:beta-Lactamases
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D001618:beta-Lactamases; C063912:carbapenemase