Assessment of hypermucoviscosity as a virulence factor for experimental Klebsiella pneumoniae infections: Comparative virulence analysis with hypermucoviscosity-negative strain

Yi Chun Lin, Min Chi Lu, Hui Ling Tang, Hsu Chung Liu, Ching-Hsien Chen, Keh Sen Liu, Chingju Lin, Chien Shun Chiou, Ming Ko Chiang, Chuan Mu Chen, Yi Chyi Lai

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58 Scopus citations

Abstract

Background: Klebsiella pneumoniae displaying the hypermucoviscosity (HV) phenotype are considered more virulent than HV-negative strains. Nevertheless, the emergence of tissue-abscesses-associated HV-negative isolates motivated us to re-evaluate the role of HV-phenotype. Results: Instead of genetically manipulating the HV-phenotype of K. pneumoniae, we selected two clinically isolated K1 strains, 1112 (HV-positive) and 1084 (HV-negative), to avoid possible interference from defects in the capsule. These well-encapsulated strains with similar genetic backgrounds were used for comparative analysis of bacterial virulence in a pneumoniae or a liver abscess model generated in either nave or diabetic mice. In the pneumonia model, the HV-positive strain 1112 proliferated to higher loads in the lungs and blood of nave mice, but was less prone to disseminate into the blood of diabetic mice compared to the HV-negative strain 1084. In the liver abscess model, 1084 was as potent as 1112 in inducing liver abscesses in both the nave and diabetic mice. The 1084-infected diabetic mice were more inclined to develop bacteremia and had a higher mortality rate than those infected by 1112. A mini-Tn5 mutant of 1112, isolated due to its loss of HV-phenotype, was avirulent to mice. Conclusion: These results indicate that the HV-phenotype is required for the virulence of the clinically isolated HV-positive strain 1112. The superior ability of the HV-negative stain 1084 over 1112 to cause bacteremia in diabetic mice suggests that factors other than the HV phenotype were required for the systemic dissemination of K. pneumoniae in an immunocompromised setting.

Original languageEnglish (US)
Article number50
JournalBMC Microbiology
Volume11
DOIs
StatePublished - Mar 14 2011
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

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