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Type III secretion system and virulence markers highlight similarities and differences between human- and

Sylvie Mazurier1, Annabelle Merieau2, Dorian Bergeau2

  • 1INRA, UMR 1347 Agroécologie, Dijon, France.

Applied and Environmental Microbiology
|February 1, 2015
PubMed

Insights

Clinical Pseudomonas isolates revealed two distinct groups: one with thermotolerant bacteria related to Pseudomonas aeruginosa and harboring Ysc-type three secretion systems (T3SSs), and another with P. fluorescens possessing plant-like Hrp1-T3SS genes.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Genomics

Background:

  • Pseudomonas fluorescens is typically saprophytic, but clinical isolates suggest potential emerging pathogenicity.
  • The role of type three secretion systems (T3SSs) in Pseudomonas aeruginosa pathogenesis raises questions about their presence in clinical P. fluorescens.

Purpose of the Study:

  • To investigate the presence and characteristics of T3SSs in clinical P. fluorescens isolates.
  • To compare clinical isolates with plant-associated T3SS-harboring fluorescent pseudomonads.

Main Methods:

  • 16S rRNA gene sequencing for phylogenetic analysis.
  • Polymerase Chain Reaction (PCR) to detect T3SS genes.
  • Infectivity assays on animal and plant models at different temperatures.

Main Results:

  • Two distinct groups were identified among clinical isolates.
  • Thermotolerant isolates from blood infections were not P. fluorescens but related species with Ysc-T3SS genes, similar to P. aeruginosa.
  • Cystic fibrosis isolates were identified as P. fluorescens and possessed Hrp1-T3SS genes, common in plant strains.

Conclusions:

  • Clinical environments harbor diverse fluorescent pseudomonads, some distinct from P. fluorescens, potentially possessing pathogenic T3SSs.
  • P. fluorescens clinical isolates can harbor plant-associated T3SSs, suggesting potential adaptation or transfer mechanisms.

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