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Staphylococcus aureus Pneumonia: Preceding Influenza Infection Paves the Way for Low-Virulent Strains

Stefanie Deinhardt-Emmer1,2, Karoline Frieda Haupt2, Marina Garcia-Moreno1

  • 1Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, D-07747 Jena, Germany.

Toxins
|December 22, 2019
PubMed

Insights

Staphylococcus aureus pneumonia strains show enhanced invasion and cytotoxicity. However, co-infection with influenza virus allows less virulent S. aureus strains to cause severe pneumonia and high mortality.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Bacterial Pathogenesis

Background:

  • * *Staphylococcus aureus* is a bacterium that can cause severe pneumonia with high mortality rates.
  • * Virulence factors of *S. aureus* vary among clinical isolates, influencing infection severity.
  • * Co-infections, such as with influenza virus, can complicate *S. aureus* pneumonia outcomes.

Purpose of the Study:

  • * To characterize the virulent capacity of *S. aureus* isolates from different pneumonia contexts.
  • * To compare the virulence of *S. aureus* in mono-infections versus influenza virus co-infections.
  • * To investigate the role of specific virulence factors in *S. aureus*-induced pneumonia.

Main Methods:

  • * Analysis of 70 *S. aureus* strains from colonization, mono-infection pneumonia, and co-infection pneumonia.
  • * Characterization of virulence genes in the analyzed strains.
  • * Functional assays in cell culture systems to assess host-pathogen interactions, including invasion and cytotoxicity.

Main Results:

  • * *S. aureus* strains causing mono-infection pneumonia exhibited enhanced invasion and cytotoxicity against phagocytes compared to colonizing or co-infecting strains.
  • * Pneumonia strains possessed a higher prevalence of cytotoxic components.
  • * Strains from co-infection showed reduced virulence characteristics, similar to colonizing strains, yet were associated with the highest patient mortality.

Conclusions:

  • * Invasion and toxins are crucial for *S. aureus* mono-infection pneumonia.
  • * In *S. aureus*/influenza virus co-infections, even strains with low virulence can significantly worsen pneumonia severity.
  • * Understanding these distinct pathogenic mechanisms is vital for managing *S. aureus* pneumonia, especially in co-infected patients.
Keywords:
Staphylococcus aureusinfluenza viruspneumonia

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