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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Antimicrobials, Resistance and Chemotherapy
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1494772
This article is part of the Research Topic Breaking the Biofilm Barrier: Analysis of Molecular Mechanisms Underlying Biofilm Formation and Identification of Novel Antimicrobial Approaches View all articles

Inhibition of Biofilm Formation and Preformed Biofilm in Acinetobacter baumannii by Resveratrol, Chlorhexidine and Benzalkonium: Modulation of Efflux Pump Activity

Provisionally accepted
Antonella Migliaccio Antonella Migliaccio 1Maria Stabile Maria Stabile 1Maria Triassi Maria Triassi 1Emmanuelle Dé Emmanuelle Dé 2Eliana De Gregorio Eliana De Gregorio 3*Raffaele Zarrilli Raffaele Zarrilli 1*
  • 1 Public Health, Department of Public Health, School of Medicine and Surgery, University of Naples Federico II, Naples, Italy, Italy
  • 2 Univ Rouen Normandie, INSA Rouen Normandie, CNRS, PBS UMR 6270, F-76000 Rouen, France, Rouen, France
  • 3 Department of Molecular Medicine and Medical Biotechnology, School of Medicine and Surgery, University of Naples Federico II, Naples, Campania, Italy

The final, formatted version of the article will be published soon.

    The persistence of Acinetobacter baumannii in the contaminated environment is sustained by tolerance to biocides and ability to growth as biofilm. The aim of the study was to analyze the susceptibility of A. baumannii biofilms to chlorhexidine (CHX) and benzalkonium (BZK) biocides and the ability of natural monomeric stilbenoid resveratrol (RV) to modulate the phenomenon. Methods: Biofilm formation and preformed biofilm were tested by Crystal violet and tetrazolium salt reduction assay, respectively. Analysis of efflux pump (EP) expression during biofilm growth was performed by Real-time RT-PCR assays. Results: CHX and BZK at ¼ and ½ MICs alone or in combination inhibited biofilm growth of A. baumannii ATCC 19606, 4190 and 3909 strains. RV at 32 mg/L and CHX and BZK at ¼ or ½ MICs showed a synergistic effect and completely inhibited biofilm formation in all A. baumannii strains. Similarly, RV at 32 mg/L and CHX and BZK at ½ MIC significantly inhibited air-liquid biofilm formation of A. baumannii ATCC 19606, 4190 and 3909 strains. The inactivation of AdeB and AdeJ RND EPs in A. baumannii ATCC19606 increased the susceptibility to CHX and BZK alone or in the presence of 32 mg/L RV. Concordantly, carbonyl cyanide m-chlorophenylhydrazine (CCCP) increased the susceptibility to CHX, BZK and RV and dose-dependently inhibited biofilm formation in A. baumannii ATCC 19606, 4190 and 3909 strains. RV at 32 mg/L inhibited basal and CHX-induced EP genes expression, while increased EP gene expression in the presence of BZK during A. baumannii ATCC19606 biofilm growth. In addition, CHX and BZK alone or in combination dose-dependently reduced preformed biofilm of all A. baumannii strains. The combination of RV with CHX and BZK additively decreased minimal biofilm eradicating concentrations in A. baumannii strains.Conclusions: These results demonstrate that: i) CHX and BZK alone or in the presence of RV inhibit biofilm growth and preformed biofilm in A. baumannii; ii) tolerance to CHX and BZK during biofilm growth is dependent on the activation of AdeB and AdeJ EPs; iii) the inhibitory effect of RV on biofilm growth is mediated by the inhibition of EP genes expression in A. baumannii.

    Keywords: Acinetobacter baumannii, biocides, resveratrol, biofilm growth, Preformed biofilm, efflux pumps

    Received: 11 Sep 2024; Accepted: 28 Nov 2024.

    Copyright: © 2024 Migliaccio, Stabile, Triassi, Dé, De Gregorio and Zarrilli. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Eliana De Gregorio, Department of Molecular Medicine and Medical Biotechnology, School of Medicine and Surgery, University of Naples Federico II, Naples, Campania, Italy
    Raffaele Zarrilli, Public Health, Department of Public Health, School of Medicine and Surgery, University of Naples Federico II, Naples, 80131, Italy, Italy

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