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Replication of the Ordered, Nonredundant Library of Pseudomonas aeruginosa strain PA14 Transposon Insertion Mutants
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Emergence of multidrug-resistant mutants is increased under antibiotic selective pressure in Pseudomonas aeruginosa

A Alonso1, E Campanario, J L Martínez

  • 1Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CSIC), Cantoblanco, Madrid, Spain.

Microbiology (Reading, England)
|October 28, 1999
PubMed

Insights

Long-term exposure to tetracycline significantly increases the mutation rate of Pseudomonas aeruginosa, promoting the emergence of multidrug-resistant (MDR) strains. These resistant mutants exhibit reduced susceptibility to various antibiotics.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Infectious Diseases

Background:

  • Pseudomonas aeruginosa is a critical opportunistic pathogen causing hospital-acquired infections, particularly in cystic fibrosis patients.
  • Multidrug-resistance (MDR) is a common phenotype in hospital isolates due to antibiotic selective pressure.

Purpose of the Study:

  • To investigate the effect of the bacteriostatic antibiotic tetracycline on the mutation rate of Pseudomonas aeruginosa.
  • To characterize the resulting MDR mutants and understand the mechanism of resistance emergence.

Main Methods:

  • Incubation of Pseudomonas aeruginosa PAO1 with tetracycline over an extended period.
  • Analysis of mutation rates, antibiotic susceptibility, and outer-membrane protein profiles of resulting mutants.

Main Results:

  • Tetracycline treatment increased the mutation rate of P. aeruginosa by several orders of magnitude.
  • Obtained tetracycline-resistant mutants were stable and displayed cross-resistance to other antibiotic classes.
  • These mutants possessed a novel outer-membrane protein absent in the wild-type strain.

Conclusions:

  • Incubation with tetracycline promotes the emergence of MDR mutants in Pseudomonas aeruginosa.
  • Findings offer insights into the rapid development of antibiotic resistance in bacterial populations during infections.
  • The study supports the adaptive mutation phenomenon under stress conditions.

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