Antibiofilm and antivirulence efficacy of myrtenol enhances the antibiotic susceptibility of Acinetobacter baumannii

Sci Rep. 2020 Dec 15;10(1):21975. doi: 10.1038/s41598-020-79128-x.

Abstract

Acinetobacter baumannii (AB) is rising as a human pathogen of critical priority worldwide as it is the leading cause of chronic opportunistic infections in healthcare settings and the condition is ineradicable with antibiotic therapy. AB possesses the ability to form biofilm on abiotic as well as biotic surfaces which plays a major role in its pathogenesis and resistance in clinical settings. Hence, the demand for an alternative therapy to combat the biofilm-associated infections is increasing. The present study explored the antibiofilm potential of myrtenol, a bicyclic monoterpene present in various plants against reference and clinical strains of AB. Myrtenol (200 μg/mL) exhibited a strong antibiofilm activity without exerting any harmful effect on growth and metabolic viability of AB strains. Microscopic analyses confirmed the reduction in the biofilm thickness and surface coverage upon myrtenol treatment. Especially, myrtenol was found to be effective in disrupting the mature biofilms of tested AB strains. Furthermore, myrtenol inhibited the biofilm-associated virulence factors of AB strains such as extracellular polysaccharide, cell surface hydrophobicity, oxidant resistance, swarming and twitching motility. Transcriptional analysis unveiled the suppression of the biofilm-associated genes such as bfmR, csuA/B, bap, ompA, pgaA, pgaC, and katE by myrtenol. Notably, myrtenol improved the susceptibility of AB strains towards conventional antibiotics such as amikacin, ciprofloxacin, gentamicin and trimethoprim. Thus, the present study demonstrates the therapeutic potential of myrtenol against biofilm-associated infections of AB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter baumannii / drug effects
  • Acinetobacter baumannii / growth & development
  • Acinetobacter baumannii / pathogenicity*
  • Acinetobacter baumannii / physiology*
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Adhesion / drug effects
  • Bicyclic Monoterpenes / pharmacology*
  • Biofilms / drug effects*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Gene Expression Regulation, Bacterial / drug effects
  • Hydrophobic and Hydrophilic Interactions
  • Microbial Sensitivity Tests
  • Models, Biological
  • Movement
  • Oxidants / toxicity
  • Polysaccharides / pharmacology
  • Virulence / drug effects

Substances

  • Anti-Bacterial Agents
  • Bicyclic Monoterpenes
  • Oxidants
  • Polysaccharides
  • myrtenol