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Reduction of virulence factor pyocyanin production in multidrug-resistant Pseudomonas aeruginosa

Katsuhiro Fuse1, Shigeru Fujimura, Toshiaki Kikuchi

  • 1Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.

Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy
|August 7, 2012
PubMed

Insights

Metallo-β-lactamase (MBL)-producing multidrug-resistant (MDR) Pseudomonas aeruginosa strains exhibit reduced pyocyanin production. This decreased pyocyanin may explain their lower pathogenicity and tendency towards colonization rather than infection.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Nosocomial infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa are a global health concern.
  • Metallo-β-lactamase (MBL) production contributes to MDR in P. aeruginosa.
  • Pyocyanin, a pigment produced by P. aeruginosa, is a key virulence factor.

Purpose of the Study:

  • To investigate the pyocyanin production capability of MBL-producing MDR P. aeruginosa.
  • To correlate pyocyanin production with the expression of pyocyanin synthesis genes (phzM and phzS).
  • To assess the potential impact of MBL production and MDR on P. aeruginosa pathogenicity.

Main Methods:

  • Collected 50 clinical P. aeruginosa isolates (20 MDR) from Japanese hospitals.
  • Measured pyocyanin chromaticity, luminosity, and quantity.
  • Quantified phzM and phzS gene expression.
  • Transduced MBL genes into P. aeruginosa to induce MDR and observed changes in pyocyanin production.

Main Results:

  • MDR strains exhibited significantly lower pyocyanin quantities (0.015 μg) compared to non-MDR strains (0.41 μg).
  • MDR strains showed reduced expression of phzM (11%) and phzS (14%) genes.
  • Acquisition of MBL genes and MDR led to decreased pyocyanin production.
  • MBL-producing MDR P. aeruginosa strains displayed less intense coloration (yellow-green) versus non-MDR strains (blue-green).

Conclusions:

  • MBL-producing MDR P. aeruginosa strains have a reduced ability to produce pyocyanin.
  • This diminished pyocyanin production may contribute to lower pathogenicity in these strains.
  • MDR P. aeruginosa may be more prone to subclinical colonization than active infection.

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