Eucalyptol inhibits biofilm formation of Streptococcus pyogenes and its mediated virulence factors

• Published in: Journal of medical microbiology Vol. 69; no. 11; pp. 1308 - 1318
• Main Authors: Vijayakumar, Karuppiah, Manigandan, Vajravelu, Jeyapragash, Danaraj, Bharathidasan, Veeraiyan, Anandharaj, Balaiyan, Sathya, Madhavan
• Format: Journal Article
• Language: English
• Published: England 01-11-2020
• Subjects: Anti-Bacterial Agents - pharmacology; Bacterial Adhesion - drug effects; Biofilms - drug effects; Eucalyptol - pharmacology; Gene Expression; Hydrophobic and Hydrophilic Interactions; Microbial Sensitivity Tests; Streptococcus pyogenes - drug effects; Streptococcus pyogenes - genetics; Streptococcus pyogenes - pathogenicity; Virulence; Virulence Factors - genetics; Eucalyptol; Streptococcus pyogenes; cell surface hydrophobicity; covR/S; antibiofilm activity
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/jmm.0.001253

is a diverse virulent synthesis pathogen responsible for invasive systemic infections. Establishment of antibiotic resistance in the pathogen has produced a need for new antibiofilm agents to control the biofilm formation and reduce biofilm-associated resistance development.
The present study investigates the
antibiofilm activity of eucalyptol against
.
The antibiofilm potential of eucalyptol was assessed using a microdilution method and their biofilm inhibition efficacy was visualized by microscopic analysis. The biochemical assays were performed to assess the influence of eucalyptol on virulence productions. Real-time PCR analysis was performed to evaluate the expression profile of the virulence genes.
Eucalyptol showed significant antibiofilm potential in a dose-dependent manner without affecting bacterial growth. Eucalyptol at 300 µg ml
(biofilm inhibitory concentration) significantly inhibited the initial stage of biofilm formation in
. However, eucalyptol failed to diminish the mature biofilms of
at biofilm inhibitory concentration and it effectively reduced the biofilm formation on stainless steel, titanium, and silicone surfaces. The biochemical assay results revealed that eucalyptol greatly affects the cell-surface hydrophobicity, auto-aggregation, extracellular protease, haemolysis and hyaluronic acid synthesis. Further, the gene-expression analysis results showed significant downregulation of virulence gene expression upon eucalyptol treatment.
The present study suggests that eucalyptol applies its antibiofilm assets by intruding the initial biofilm formation of
. Supplementary studies are needed to understand the mode of action involved in biofilm inhibition.