Anti-Biofilm Inhibitory Synergistic Effects of Combinations of Essential Oils and Antibiotics.

Antonio Rosato,Maria Lisa Clodoveo,Lara Salvagno,Filomena Corbo,Alessia Carocci,Sabina Sblano,Giuseppe Fracchiolla

doi:10.3390/antibiotics9100637

Antonio Rosato, Maria Lisa Clodoveo + Show 5 more

Open Access

https://doi.org/10.3390/antibiotics9100637

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Abstract

In recent years, the increase of bacteria antibiotic- resistance has been a severe problem for public health. A useful solution could be to join some phytochemicals naturally present in essential oils (EOs) to the existing antibiotics, with the aim to increase their efficacy in therapies. According to in vitro studies, EOs and their components could show such effects. Among them, we studied the activity of Cinnammonum zeylanicum, Mentha piperita, Origanum vulgare, and Thymus vulgaris EOs on bacterial biofilm and their synergism when used in association with some common antibiotics such as norfloxacin, oxacillin, and gentamicin. The chemical composition of EOs was determined using gas chromatography (GC) coupled with mass spectrometry (MS) techniques. The EOs drug efficacy was evaluated on four different strains of Gram-positive bacteria forming biofilms. The synergistic effects were tested through the chequerboard microdilution method. The association EOs-antibiotics showed a strong destruction of the biofilm growth of the four bacterial species considered. The interaction of norfloxacin with EOs was the most effective in all the tested combinations against the strains object of this study. These preliminary results suggest the formulation of a new generation of antimicrobial agents based on a combination of antimicrobial compounds with different origin.

Highlights

The dramatic increase in anti-microbic resistance (AMR) for pathogenic bacteria represents a serious problem for human health [1]
essential oils (EOs) were analyzed by gas chromatography hyphenated with mass spectrometry (GC/MS) technique
The combination of EOs with antimicrobials is the origin of a significant reduction in the concentration of gentamicin and the other two antibiotics—oxacillin and norfloxacin—used to inhibit the biofilms

Summary

Introduction

The dramatic increase in anti-microbic resistance (AMR) for pathogenic bacteria represents a serious problem for human health [1]. It occurs by the mechanism of selective pressure of the antibiotic. AMR leads to higher medical cost, prolonged hospital stays and increased mortality [2,3,4]. For this reason, a solution is to hinder the uncontrolled use of antibiotics and search for new ones [3]. It is essential to decrease the use of the antibiotic in the veterinary and agricultural fields and could be interesting to exploit synergistic interactions with natural products such as plant products [5]

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