title: Regulator of the mucoid phenotype A gene increases the virulent ability of extended-spectrum beta-lactamase-producing serotype non-K1/K2 Klebsiella pneumonia.
abstract: BACKGROUND
  To determine whether the presence of a capsule regulator gene [i.e., regulator of mucoid phenotype A (rmpA) gene] contributes to virulence on extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) with serotype non-K1/K2 strains.
  
  
  METHODS
  Twenty-eight ESBL-KP and non-ESBL-KP isolates were collected from the Tri-Service General Hospital (Taipei, Taiwan). The impact of the virulent rmpA gene in different capsular polysaccharide serotypes on ESBL-KP and non-ESBL-KP isolates was studied by a neutrophil phagocytosis reaction, a serum bactericidal assay, and an animal survival model.
  
  
  RESULTS
  Resistance to broad spectrum antibiotics was more prevalent in ESBL-KP strains than in non-ESBL-KP strains (p < 0.01). The ESBL-KP strains had different molecular patterns from non-ESBL-KP strains, based on pulsed-field gel electrophoresis. The frequency of serum-resistant isolates was the highest among ESBL-KP strains with rmpA (i.e., rmpA(+)) [71.4% (5/7)] than among of non-ESBL-KP rmpA(+) strains [42.8% (6/14)], ESBL-KP strains without rmpA (rmpA(-)) [33.3% (7/21)], and non-ESBL-KP rmpA(-) strains [14.2% (2/14)]. The most significant increase in neutrophil resistance occurred in the ESBL-KP rmpA(+) strains in comparison to the non-ESBL-KP rmpA(+), ESBL-KP rmpA(-), and non-ESBL-KP rmpA(-) strains (p < 0.01). The results of the animal survival model were compatible with the neutrophil phagocytosis reaction and serum bactericidal assay.
  
  
  CONCLUSIONS
  We conclude that the pathogenic potential is greater in rmpA(+) ESBL-KP strains than in rmpA(-) ESBL-KP and non-ESBL-KP strains.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Department of Internal Medicine, Songshan Branch of Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Hsin-An
authors.initials: HA
authors.lastname: Lin
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Huang
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Kao-Ming
authors.initials: KM
authors.lastname: Yeh
authors.affiliation: National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Taipei, Taiwan.
authors.forename: L K
authors.initials: LK
authors.lastname: Siu
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Institute of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan. Electronic address: jclin@ndmctsgh.edu.tw.
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016667:Bacterial Capsules / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007710:Klebsiella Infections / Q000188:drug therapy; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009504:Neutrophils / Q000276:immunology; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology; D065288:Serogroup; D013624:Taiwan; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C512267:RmpA protein, Klebsiella pneumoniae; D001618:beta-Lactamases
keywords: Klebsiella pneumoniae; regulator of mucoid phenotype A; β-lactamase-producing Klebsiella pneumonia