Loss of a 29-kilodalton outer membrane protein in Acinetobacter baumannii is associated with imipenem resistance

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Separation of the Cell Envelope for Gram-negative Bacteria into Inner and Outer Membrane Fractions with Technical Adjustments for Acinetobacter baumannii
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Separation of the Cell Envelope for Gram-negative Bacteria into Inner and Outer Membrane Fractions with Technical Adjustments for Acinetobacter baumannii

Published on: April 10, 2020

Adriana S Limansky1, María Alejandra Mussi, Alejandro M Viale

  • 1Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000 Rosario, Argentina.

Journal of Clinical Microbiology
|November 28, 2002
PubMed

Insights

Acinetobacter baumannii resistance to imipenem (IPM) is linked to the loss of a specific 29-kDa outer membrane protein (OMP). This OMP loss occurs with IPM exposure and sodium salicylate treatment, suggesting its role in IPM resistance.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Antimicrobial Resistance

Background:

  • Acinetobacter baumannii is a significant multidrug-resistant pathogen.
  • Carbapenem resistance is a growing concern in A. baumannii infections.
  • Mechanisms of imipenem resistance in A. baumannii are not fully understood.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying imipenem (IPM) resistance in multidrug-resistant Acinetobacter baumannii.
  • To identify potential outer membrane protein (OMP) alterations associated with IPM resistance.

Main Methods:

  • Comparative analysis of outer membrane protein (OMP) profiles between imipenem-sensitive and imipenem-resistant strains.
  • Genomic comparison of related strains to identify genetic differences.
  • Induction of imipenem resistance through chemical treatment (sodium salicylate) and antibiotic selection.
  • Detection of carbapenemase activity.

Main Results:

  • A conspicuous loss of a 29-kDa outer membrane protein (OMP) was observed in an imipenem-resistant Acinetobacter baumannii strain (Ab242) compared to a sensitive strain (Ab288).
  • No carbapenemase activity was detected in the analyzed strains.
  • Treatment of the sensitive strain with sodium salicylate induced imipenem resistance and resulted in the loss of the 29-kDa OMP.
  • Imipenem-resistant clones selected through serial subculturing also exhibited the absence of this 29-kDa OMP.

Conclusions:

  • The loss of a specific 29-kDa outer membrane protein (OMP) is strongly associated with imipenem resistance in Acinetobacter baumannii.
  • This OMP appears to play a crucial role in maintaining susceptibility to imipenem.
  • Mechanisms other than carbapenemase production are involved in imipenem resistance in these isolates.

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