An AcrAB-mediated multidrug-resistant phenotype is maintained following restoration of wild-type activities by efflux pump genes and their regulators

A. Martins, C. Iversen, L. Rodrigues, G. Spengler, J. Ramos, W. V. Kern, I. Couto, M. Viveiros, S. Fanning, J. M. Pages, L. Amaral

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

In this study, we aimed to answer the following question: 'How does a bacterium become so resistant to a given antibiotic even though the levels of antibiotic to which it has become resistant remained constant in the patient?' Escherichia coli AG100 strain induced to high-level resistance due to overexpression of an AcrAB efflux pump was serially cultured in 10 mg/L tetracycline for 60 passages. Between each passage it became increasingly resistant to tetracycline, β-lactams and quinolones with concomitant restoration of wild-type AcrAB activity. Because the multidrug-resistant phenotype could not be reversed with transfer to drug-free medium or with efflux pump inhibitors, it may have resulted from activation of a 'mutator gene' system that reduced the 'energy consumption' associated with an overexpressed efflux pump system.

Original languageEnglish
Pages (from-to)602-604
Number of pages3
JournalInternational Journal of Antimicrobial Agents
Volume34
Issue number6
DOIs
Publication statusPublished - Dec 1 2009

Keywords

  • Efflux pumps
  • MDR phenotype
  • Overexpression

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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