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Organic solvent-tolerant mutants of Pseudomonas aeruginosa display multiple antibiotic resistance

X Z Li1, K Poole

  • 1Department of Microbiology and Immunology, Queen's University, Kingston, ON, Canada.

Canadian Journal of Microbiology
|June 1, 1999
PubMed

Insights

Mutant Pseudomonas aeruginosa, tolerant to organic solvents, showed increased antibiotic resistance. This resistance is linked to the MexAB-OprM efflux system, highlighting environmental pollutants

Area of Science:

  • Microbiology
  • Molecular Biology
  • Environmental Science

Background:

  • Pseudomonas aeruginosa is an opportunistic pathogen known for its intrinsic and acquired resistance to antimicrobial agents.
  • Multidrug efflux systems play a crucial role in bacterial resistance mechanisms.
  • Organic solvent tolerance in bacteria can be linked to multidrug resistance phenotypes.

Purpose of the Study:

  • To investigate the relationship between organic solvent tolerance and multidrug resistance in Pseudomonas aeruginosa.
  • To identify the specific efflux systems involved in the observed phenotypes.

Main Methods:

  • Selection of organic solvent-tolerant mutants of Pseudomonas aeruginosa in the presence of hexane.
  • Assessment of antimicrobial susceptibility profiles of the selected mutants.
  • Western immunoblotting to analyze the expression levels of multidrug efflux systems (MexAB-OprM, MexEF-OprN).
  • Sequence analysis of the mexR gene, a repressor of the mexAB-oprM operon.

Main Results:

  • Organic solvent-tolerant mutants exhibited cross-resistance to structurally unrelated antimicrobial agents (beta-lactams, fluoroquinolones, chloramphenicol, tetracycline, novobiocin).
  • Increased expression of the MexAB-OprM efflux system and decreased expression of the MexEF-OprN system were observed in tolerant mutants.
  • Mutations in the mexR repressor gene were identified in two solvent-tolerant mutants.

Conclusions:

  • The MexAB-OprM efflux system is critical for organic solvent tolerance in Pseudomonas aeruginosa.
  • Environmental pollutants can select for bacteria exhibiting medically relevant antibiotic-resistant phenotypes.
  • This study underscores the link between environmental exposure and the emergence of multidrug resistance in pathogenic bacteria.

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