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The effect of a bacteriophage on diversification of the opportunistic bacterial pathogen, Pseudomonas aeruginosa

Michael A Brockhurst1, Angus Buckling, Paul B Rainey

  • 1Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK. brockhurst@isem.univ-montp2.fr

Proceedings. Biological Sciences
|July 12, 2005
PubMed

Insights

Bacteriophage PP7 drives diversity in Pseudomonas aeruginosa lung infections by causing evolution of resistant bacterial variants. These resistant strains exhibit different ecological traits and come with a fitness cost, impacting infection persistence in cystic fibrosis patients.

Area of Science:

  • Microbiology
  • Evolutionary Biology
  • Infectious Diseases

Background:

  • Pseudomonas aeruginosa is an opportunistic pathogen frequently found in cystic fibrosis (CF) lungs.
  • CF lung infections exhibit diverse P. aeruginosa phenotypes, contributing to persistent infections.
  • The origins of this bacterial diversity remain incompletely understood, with factors like lung environment and phage predation being investigated.

Purpose of the Study:

  • To investigate the role of bacteriophage PP7 in driving morphological diversification of Pseudomonas aeruginosa.
  • To understand the evolutionary dynamics and ecological consequences of phage-host interactions in a CF lung context.

Main Methods:

  • Experimental evolution of P. aeruginosa populations in the presence and absence of bacteriophage PP7.
  • Characterization of bacterial colony morphology (small-rough vs. large-diffuse).
  • Assessment of bacterial resistance mechanisms and associated fitness costs.

Main Results:

  • Bacteriophage PP7 induced cycles of morphological diversification, leading to the emergence of small-rough colony variants alongside large-diffuse morphs.
  • In the absence of phage, only the large-diffuse wild-type morphology was observed.
  • Two distinct types of phage-resistant bacteria evolved, each with unique ecological phenotypes and a measurable cost of resistance.

Conclusions:

  • Parasitic bacteriophages, such as PP7, are significant drivers of bacterial diversity and evolution within host environments like the CF lung.
  • The emergence of phage-resistant bacterial variants with differing phenotypes and fitness costs can influence the persistence of P. aeruginosa infections.
  • Understanding phage-host dynamics is crucial for comprehending bacterial adaptation and infection progression in cystic fibrosis.

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