Pulmonary and systemic host response to Streptococcus pneumoniae and Klebsiella pneumoniae bacteremia in normal and immunosuppressed mice.

Published

Journal Article

Mortality related to bacteremic pneumonia remains high, and the role of sepsis in inflammation, pulmonary injury, and death remains unclear, mostly in leukopenic states. In the present study, the microbiology, histopathology, and host response to Streptococcus pneumoniae and Klebsiella pneumoniae infection were determined in an experimental model of bacteremia in immunocompetent and leukopenic mice. Leukocyte depletion by cyclophosphamide did not impair the early clearance of pneumococci from blood but facilitated growth in lungs. By contrast, klebsiellae rapidly grew in blood of leukopenic mice. These observations suggest that tissue-based phagocytes and circulating leukocytes, respectively, play prominent roles in S. pneumoniae and K. pneumoniae eradication. The kinetics of leukocyte recruitment in lungs during S. pneumoniae bacteremia suggested early strong inflammation in immunocompetent mice that is associated with tumor necrosis factor alpha release and histological disorders, including cell debris and surfactant in alveolar spaces. Leukocyte depletion further stimulated pulmonary capillary leakage both in S. pneumoniae and K. pneumoniae bacteremia, which seemed attributable to bacterial virulence factors. Nitric oxide production did not differ significantly among groups. Leukopenia and low platelet counts characterized the late stage of bacteremia for both strains, but only K. pneumoniae altered renal function. Understanding the pathogenesis of bacteremia will help establish beneficial therapies for both sepsis and pneumonia.

Full Text

Duke Authors

Cited Authors

  • Wang, E; Ouellet, N; Simard, M; Fillion, I; Bergeron, Y; Beauchamp, D; Bergeron, MG

Published Date

  • September 2001

Published In

Volume / Issue

  • 69 / 9

Start / End Page

  • 5294 - 5304

PubMed ID

  • 11500398

Pubmed Central ID

  • 11500398

International Standard Serial Number (ISSN)

  • 0019-9567

Digital Object Identifier (DOI)

  • 10.1128/iai.69.9.5294-5304.2001

Language

  • eng

Conference Location

  • United States