Relationship Between the Quorum Network (Sensing/Quenching) and Clinical Features of Pneumonia and Bacteraemia Caused

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Laura Fernandez-Garcia1, Antón Ambroa1, Lucia Blasco1

  • 1Microbiology Department-Biomedical Research Institute A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain.

Frontiers in Microbiology
|January 9, 2019
PubMed

Insights

Acinetobacter baumannii quorum sensing and quenching network impacts pneumonia virulence and secondary bloodstream infections. Lower aidA gene expression in bacteraemic pneumonia suggests altered Quorum Sensing/Quenching regulation.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Molecular Biology

Background:

  • Acinetobacter baumannii is a major cause of hospital-acquired infections, particularly pneumonia.
  • The Quorum Sensing (QS) and Quorum Quenching (QQ) network regulates virulence factors in A. baumannii.
  • Understanding the QS/QQ network's role in pneumonia and bacteraemia is crucial for infection control.

Purpose of the Study:

  • To investigate the relationship between the Quorum network in A. baumannii and the development of pneumonia and bacteraemia.
  • To analyze the expression of the aidA gene (QQ enzyme) in clinical strains under different conditions.
  • To evaluate the virulence of A. baumannii strains in an in vivo model.

Main Methods:

  • Analysis of 30 clinical A. baumannii strains from a multicentre study.
  • Measurement of aidA gene expression in response to environmental stressors (3-oxo-C12-HSL, H2O2).
  • In vivo virulence testing using the Galleria mellonella infection model with wild-type and abaI-deficient strains.

Main Results:

  • Lower aidA gene expression was observed in strains from patients with bacteraemic pneumonia compared to non-bacteraemic pneumonia.
  • aidA expression in bacteraemic pneumonia strains was not regulated by 3-oxo-C12-HSL or H2O2, unlike non-bacteraemic strains.
  • The abaI-deficient mutant showed reduced mortality in Galleria mellonella compared to the wild-type strain.

Conclusions:

  • The QS/QQ network, involving abaR, abaI, and aidA genes, influences the development of secondary bacteraemia in pneumonia.
  • Alterations in QS/QQ regulation are associated with increased virulence of A. baumannii.
  • Targeting the QS/QQ network may offer novel therapeutic strategies against A. baumannii infections.
Keywords:
Acinetobacterbacteraemiapneumoniaquorumsensing/quenching

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