Detection of Anti-Biofilm Activity of Peppermint Essential Oil in S. aureus, E. coli and P. aeruginosa

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Résumé

Microbial biofilms pose a public health problem and are difficult to eliminate with conventional
antimicrobial treatments. This study aimed to detect the anti-biofilm activity of natural peppermint essential oil
against biofilm-forming bacterial strains. Sixty (60) strains, including P. aeruginosa (20), S. aureus (20), and E. coli
(20), from clinical and food sources, were included in this study. The antibacterial activity of peppermint essential
oil was determined by the Muller Hinton agar diffusion method. Phenotypic biofilm detection and the anti-biofilm
activity of peppermint essential oil were performed using the tube method. Molecular detection of biofilm-forming
genes (PelA, PslA, and ppyR) was carried out using PCR. Peppermint essential oil exhibited bactericidal activity
against foodborne and clinical strains of E. coli and S. aureus. The median number of biofilms formed ranged from
0.8 ± 0.4 to 1.4 ± 0.4 (clinical strains) and from 0.7 ± 0.4 to 1.1 ± 0.2 (foodborne strains). The biofilm-forming genes
PelA, PslA, and ppyR were detected in P. aeruginosa with prevalences ranging from 40% to 80% (clinical strains)
and from 40% to 60% (foodborne strains). The prevalence of the PelA and PslA genes in S. aureus and E. coli
ranged from 20% to 40% (clinical strains) and from 10% to 40% (foodborne strains). A significant reduction of
between 101.7% and 274.8% (P<0.01) was observed in clinical and food strains at Raw peppermint (RP) doses
ranging from 0.2% to 2%. At 0.1% of Raw peppermint (RP), a negligible increase of between 21.2% and 23.3% was
observed in clinical strains of P. aeruginosa and S. aureus. Controlling and eliminating bacterial biofilms using local
natural essential oil represents a significant therapeutic advance.

Mots-clés

Biofilm, anti-biofilm activity, Peppermint, P. aeruginosa, S. aureus and E. coli