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Antibiotic resistance and molecular typing of Pseudomonas aeruginosa: focus on imipenem

Ana Lúcia Peixoto de Freitas1, Afonso Luis Barth

  • 1Federal University of Rio Grande do Sul, Pharmacy School, Clinical Hospital of Porto Alegre, Cardiology Institute, Porto Alegre, RS, Brazil. usha@via-rs.net

The Brazilian Journal of Infectious Diseases : an Official Publication of the Brazilian Society of Infectious Diseases
|May 1, 2002
PubMed

Insights

Molecular typing revealed identical imipenem-resistant Pseudomonas aeruginosa clones in two hospitals, but no widespread spread between facilities. Antimicrobial susceptibility profiles did not effectively determine isolate relatedness.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Molecular Epidemiology

Background:

  • Pseudomonas aeruginosa is an opportunistic pathogen frequently associated with hospital-acquired infections.
  • Understanding the genetic relatedness and antimicrobial resistance patterns of P. aeruginosa isolates is crucial for infection control.

Purpose of the Study:

  • To assess the relatedness of Pseudomonas aeruginosa isolates from three hospitals in Porto Alegre, Brazil.
  • To determine antimicrobial resistance profiles and identify potential clonal spread.

Main Methods:

  • Disk diffusion and E-test for antimicrobial susceptibility testing against 8 agents.
  • Macrorestriction analysis for molecular typing of P. aeruginosa isolates.
  • Analysis of 124 isolates from three distinct hospitals.

Main Results:

  • Susceptibility frequencies varied, with 43.9% for carbenicillin and 87.7% for ceftazidime.
  • Imipenem-resistant isolates showed cross-resistance to carbenicillin (70%), but some remained susceptible to ceftazidime and cefepime.
  • Molecular typing identified 66 distinct strains, demonstrating high discriminatory power.
  • Identical clones of imipenem-resistant P. aeruginosa were found in two hospitals, but no inter-hospital spread or infection clustering was observed.

Conclusions:

  • Antimicrobial susceptibility profiles were insufficient for determining P. aeruginosa isolate relatedness.
  • Macrorestriction analysis effectively identified distinct strains and clonal relationships.
  • While related imipenem-resistant P. aeruginosa isolates were identified within hospitals, evidence suggests limited clonal spread between the facilities studied.

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