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Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
05:06

Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System

Published on: January 5, 2024

Efflux-mediated antibiotic resistance in Acinetobacter spp

Sébastien Coyne1, Patrice Courvalin, Bruno Périchon

  • 1Institut Pasteur, Unité des Agents Antibactériens, 28 Rue du Docteur Roux, 75724 Paris Cedex 15, France.

Antimicrobial Agents and Chemotherapy
|December 22, 2010
PubMed

Insights

Multidrug resistance in Acinetobacter baumannii is significantly driven by increased expression of chromosomal efflux pumps, particularly resistance-nodulation-division (RND) systems, rather than solely gene acquisition.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Acinetobacter baumannii is a major cause of nosocomial infections, especially in intensive care units.
  • Multidrug resistance (MDR) in A. baumannii was previously attributed mainly to acquired resistance genes.
  • Emerging evidence highlights the critical role of increased expression of chromosomal efflux systems in MDR.

Purpose of the Study:

  • To investigate the role of efflux pump gene expression in multidrug resistance in Acinetobacter baumannii.
  • To identify the prevalent efflux pump systems contributing to MDR in this opportunistic pathogen.

Main Methods:

  • Analysis of gene expression levels of various efflux pump systems.
  • Identification of mutations in regulatory genes associated with efflux pump overexpression.
  • Characterization of the substrate range and contribution of different efflux pumps to resistance.

Main Results:

  • Resistance-nodulation-division (RND) systems are the most prevalent pumps in multiply resistant A. baumannii.
  • Overexpression of the AdeABC system, due to mutations in adeRS, is a primary MDR mechanism.
  • Other RND (AdeFGH), non-RND (CraA, AmvA, AbeM, AbeS), and acquired efflux pumps (MFS, SMR) also contribute to resistance.

Conclusions:

  • Increased expression of chromosomal efflux systems, especially RND pumps like AdeABC, is a key driver of MDR in A. baumannii.
  • While intrinsic pumps like AdeIJK contribute to natural resistance, their overexpression is limited by toxicity.
  • Understanding these efflux mechanisms is crucial for developing strategies to combat MDR infections caused by A. baumannii.

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