Thymbra capitata essential oil has a significant antimicrobial activity against methicillin-resistant Staphylococcus aureus pre-formed biofilms

Abstract

Methicillin‐resistant Staphylococcus aureus (MRSA) is a multidrug‐resistant opportunistic pathogen with a great ability to form biofilms. Herein, the antimicrobial potential of Thymbra capitata essential oil (EO) against MRSA biofilms was investigated. The determination of the minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC) of the T. capitata EO was first investigated on a group of clinical isolates from septicaemias, diabetic foot ulcers and osteomyelitis. Biofilms were incubated with the EO at the MLC and its anti‐biofilm potential was investigated. A strong antimicrobial activity was observed, with MIC and MLC values between 0·32 and 0·64 mg l−1. However, the concentration of EO necessary for the eradication of planktonic cells was insufficient to significantly reduce the biofilm biomass of some isolates. Nevertheless, cell culturability and overall cellular metabolism was strongly reduced in all biofilms tested, only when the EO was tested. Contrary to the tested antibiotics, T. capitata EO showed a significant antimicrobial activity against MRSA biofilms, by reducing cellular metabolism and cellular culturability.

Antimicrobial Evaluation of Sequentially extracted Leaf of Vernonia auriculifera Hiern (Rejicho)

“…Besides this, antimicrobial resistance is a great challenge in current medicine [34]. Some traditionally used medicinal plants have essential oils which are effectively active against multiple pathogenic microorganisms including methicillin-resistant bacterial strains [35][36][37] Despite their use, they do have disadvantages of lack of dosage instruction, and missing scientific proof for their claim [38].…”

Chemical Composition, Antioxidant, and Antibiofilm Properties of Essential Oil from Thymus capitatus Plants Organically Cultured on the Greek Island of Lemnos

“…In a similar study, Alabdullatif et al tested the biofilm-killing efficiency of three concentrations of Tunisian T. capitatus EO (10, 20, and 30% v / v ) against Staphylococcus epidermidis biofilms (preformed on 96-well PS microtiter plates at 37 °C for 24 h) following 30 s of application (to mimic skin-disinfection practices), and they observed log reductions that ranged from 1.17 ± 0.12 to 1.42 ± 0.10 log 10 CFU/mL [ 36 ]. Almeida et al tested the biofilm-disrupting efficiency of T. capitata EO collected from plants grown in the south of Portugal against preformed biofilms (on 96-well PS microtiter plates at 37 °C for 24 h) of six clinical methicillin-resistant S. aureus (MRSA) isolates by exposing them for 24 h (at 37 °C) to 0.64 μg/mL of the EO (a concentration that was equal to its MBC) [ 37 ]. The action of the EO in that study was also compared with the action of two antibiotics with distinct mechanisms of action and commonly used to treat MRSA infections (ciprofloxacin and tetracycline) and tested at their respective peak serum concentrations [ 37 ].…”

“…Almeida et al tested the biofilm-disrupting efficiency of T. capitata EO collected from plants grown in the south of Portugal against preformed biofilms (on 96-well PS microtiter plates at 37 °C for 24 h) of six clinical methicillin-resistant S. aureus (MRSA) isolates by exposing them for 24 h (at 37 °C) to 0.64 μg/mL of the EO (a concentration that was equal to its MBC) [ 37 ]. The action of the EO in that study was also compared with the action of two antibiotics with distinct mechanisms of action and commonly used to treat MRSA infections (ciprofloxacin and tetracycline) and tested at their respective peak serum concentrations [ 37 ]. The biofilm cells of all tested isolates were significantly affected in their culturability and metabolic activity after incubation with the EO, with an observed average reduction of 2.6 log 10 CFU/mL, significantly higher than that observed with the tested antibiotics (for both, an average reduction of less than of 0.5 log 10 CFU/mL was observed).…”

“…It is generally accepted that organic agricultural systems are more profitable and more environmentally friendly than conventional farming and deliver equivalent or higher-quality products that contain less (or no) pesticide residues [ 35 ]. While there are some previous antimicrobial and antibiofilm studies employing the EO from this aromatic and medicinal species [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ], wild plants have most of the times been used to extract the oil. In addition, to the best of our knowledge, no other study has ever tested the action of T. capitatus EO against the biofilms of the aforementioned three important pathogens.…”

Genus Thymbra: A Review on Their usage areas, Phytochemical contents and Biological Activities

“…The antimicrobial activities of the plant species have been reported to be effective against P. vulgaris, E. coli, P. mirabilis, B.subtilis, S. aureus, Salmonella enterica subsp. enterica serovar Typhimurium, L. monocytogenes, Candida spp., K. pneumoniae, S. boydii, P. aeruginosa and B. cereus (Almeida et al, 2022;Charfi et al, 2019;de-Oliveira et al, 2012;Faleiro et al, 2005;Hepokur et al, 2020b;Karampoula et al, 2016;Merino et al, 2019;Moukhles et al, 2020). In a different study, it was reported that it has an antigiardia effect against Giardia trophozoites (Machado et al, 2010).…”