title: Clinical and molecular characteristics of Klebsiella pneumoniae ventilator-associated pneumonia in mainland China.
abstract: BACKGROUND
  Klebsiella pneumoniae is a prominent nosocomial pathogen that accounts for up to 10 % of all hospital-acquired infections. It is a frequent cause of ventilator-associated pneumonia (VAP). The purpose of this study was to investigate the clinical characteristics of K. pneumoniae-associated VAP and the molecular characteristics of K. pneumoniae strains.
  
  
  METHODS
  We retrospectively reviewed 70 mechanically ventilated patients with K. pneumoniae isolated. All K. pneumoniae strains were examined to determine hypermucoviscosity (HV) phenotype, capsular serotypes, virulence genes, multilocus sequence typing and antimicrobial susceptibility.
  
  
  RESULTS
  Hypermucoviscosity was found in 14 of 70 (20 %) isolates of K. pneumoniae. Among the 70 patients, 43 cases (61.4 %) developed VAP. Furthermore, VAP was more frequently induced by HV-positive K. pneumoniae (14/14, 100 %) than by HV-negative strains (29/56, 51.7 %). HV-positive K. pneumoniae-associated VAP patients were more inclined to develop bacteremia and had a higher mortality rate than HV-negative strains VAP patients. Antibiotic resistance was more frequent in HV- negative strains- than in HV- positive strains-infected patients. The prevalence of rmpA and aerobactin genes were 85.7 % and 85.7 % respectively, and serotypes K1 and K2 accounted for 14.3 % and 28.6 % of the hypermucoviscosity strains, respectively. Strains carrying rmpA and aerobactin genes were significantly associated with HV-phenotype, and rmpA and aerobactin coexisted in HV-positive strains. Multilocus sequence typing analysis identified 24 different sequence types from K. pneumoniae VAP samples.
  
  
  CONCLUSIONS
  HV-phenotype is the major virulence determinant for mechanically ventilated patients. There was a specific sequence typing (ST) distribution between HV-positive and HV-negative strains.
authors: Department of Clinical Microbiology, Henan Provincial People's Hospital, Zhengzhou, China.|Department of Infection control, Zhengzhou University People's Hospital, Zhengzhou, China.
authors: Si
authors: S
authors: Guo
authors: Department of Pathology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
authors: JingJing
authors: J
authors: Xu
authors: Department of Clinical Laboratory, Henan No. 2 Provincial people's Hospital, Zhengzhou, China.
authors: YanShuan
authors: Y
authors: Wei
authors: Department of Clinical Microbiology, Henan Provincial People's Hospital, Zhengzhou, China.
authors: JunHong
authors: J
authors: Xu
authors: Department of Clinical Microbiology, Henan Provincial People's Hospital, Zhengzhou, China. hnssmyy@163.com.
authors: Yi
authors: Y
authors: Li
authors: Department of Key Laboratory, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China. xuerui04301617@126.com.
authors: Rui
authors: R
authors: Xue
mesh_terms: D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000209:etiology; D001426:Bacterial Proteins / Q000235:genetics; D002681:China; D003428:Cross Infection / Q000382:microbiology; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics; D005260:Female; D006801:Humans; D007710:Klebsiella Infections / Q000209:etiology / Q000382:microbiology* / Q000401:mortality; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D008297:Male; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D053717:Pneumonia, Ventilator-Associated / Q000209:etiology / Q000382:microbiology* / Q000401:mortality; D012189:Retrospective Studies; D037521:Virulence Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C512267:RmpA protein, Klebsiella pneumoniae; D037521:Virulence Factors
keywords: Hypermucoviscosity; Klebsiella pneumoniae; Ventilator-associated pneumonia; Virulence determinant