Mode of Antimicrobial Action of Origanum Vulgare Essential Oil Against Clinical Pathogens

Athanasios Alexopoulos,Alexandra Nerantzaki,Athanasios Kimbaris,Maria Fournomiti,Stavros Plessas,Vasiliki Tzouti,Ioanna Mantzourani,Eugenia Bezirtzoglou,Maria Varvatou

doi:10.12944/crnfsj.5.2.07

Athanasios Alexopoulos, Alexandra Nerantzaki + Show 7 more

Open Access

https://doi.org/10.12944/crnfsj.5.2.07

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Abstract

Oregano essential oil (EO) was extracted via hydro-distillation from Origanum vulgare aromatic plant and tested for its mode of action against 16 clinically isolated strains of Escherichia coli and Staphylococcus aureus (Methicillin resistant and non-methicillin resistant). Initially, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were estimated by the broth micro-dilution method. Additionally, the extracellular concentrations of total proteins were measured in bacterial suspensions with the presence of EOs near the MIC concentrations and without the presence of EOs by using the Bradford protein assay. Ampicillin was used as a positive control. Most of S. aureus and almost half of E. coli strains exhibited relatively low MIC values when tested with the EO of oregano. Based on the protein assay a 65% of E. coli strains but over 80% of S. aureus strains exhibited a clear dose-response curve indicating that the mode of action was the disruption of the cytoplasmic membrane and cell wall. Differences in sensitivities of Gram(-) and Gram (+) bacteria on the action of EOs are known with the later been more sensitive than Gram (-). However, MRSA strains were proven resistant to the EOs when compared with their non-MRSA counterparts.

Highlights

Overuse and abuse of antibiotics resulted in antibiotic resistance of many pathogens during the last decays[1,2,3]
Oregano essential oil (EO) was most effective against S. aureus with a mean Minimum Bactericidal Concentration (MBC) of 64 μg/mL, and 128 μg/mL, respectively, for E. coli
If the protein content of the micro plate cells contained the exposed to EOs bacteria increases more than in those cells contained the unexposed bacteria it can be concluded that these proteins were the result of membrane disruption

Summary

Introduction

Overuse and abuse of antibiotics resulted in antibiotic resistance of many pathogens during the last decays[1,2,3]. To this growing resistance, many antibiotic agents has lost their efficacy with dramatic consequences in the treatment of infectious diseases. In the research for new alternative agents, phytochemicals and essential. Res. Nutr Food Sci Jour., Vol 5(2), 109-115 (2017)

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