In Vitro Synergistic Action of Certain Combinations of Gentamicin and Essential Oils

Abstract

The aim of this study was to verify the existence of synergistic antibacterial effect between four essential oils (Aniba rosaeodora, Melaleuca alternifolia, Origanum vulgare, and Pelargonium graveolens) individually combined with the antibacterial drug Gentamicin. We investigated the effectiveness in vitro of the association of essential oil/Gentamicin, against fifteen different strains of Gram positive and Gram negative bacteria. The antibacterial effects of these oils in combination with Gentamicin were evaluated by using the MHB microdilution method, while gas chromatography (GC) and GC/Mass spectrometry were used to analyze the chemical composition of the oils. A synergistic interaction was observed against all tested strains with the associations between the essential oils Aniba rosaeodora/Gentamicin and Pelargonium graveolens/Gentamicin. In particular a very strong synergistic interaction was observed against Acinetobacter baumannii ATCC 19606 (FIC index = 0.11). In contrast, the essential oils Origanum vulgare and Melaleuca alternifolia in association with Gentamicin were less effective on bacterial species growth. In vitro interaction can improve the antimicrobial effectiveness of the Gentamicin and may contribute to reduce its dose correlated to side effects.

Antioxidant and antibacterial activities of Thymus numidicus and Salvia officinalis essential oils alone or in combination

“…In our study, the effect of combinations (Table 4) was determined according to Rosato et al (2010) as following:…”

“…In addition, isobole curves are plotted. Table 4 Effect of combination of essential oil with another essential oil or antibiotic or major component (Rosato et al, 2010).…”

Essential Oils: The Ultimate Solution to Antimicrobial Resistance in <i>Escherichia coli</i>?

“…Quite a number of publications regarding the usage of essential oils and antibiotics as a combinatory therapy have indicated great success, with significant reductions in the dosage of antibiotics required to completely annihilate multidrug-resistant pathogens [31][32][33][34][35][36]. Despite this, the usage of essential oils as a component for combinatory treatment posed a few challenges in its application.…”

Essential Oils and Their Components as Modulators of Antibiotic Activity against Gram-Negative Bacteria

“…Therefore, multidrug-resistant A. baumannii is a major threat for patients with traumatic and burn injuries [21]. Linalool-rich EOs, such as rosewood ( Aniba rosaeodora Ducke, Lauraceae) and myrtle ( Myrtus communis L., Myrtaceae) EOs (60.1% and 18.32%–26.59% linalool, respectively), acted synergistically with conventional antibiotics (gentamicin, ciprofloxacin, polymyxin B) against A. baumannii reference strains and multidrug-resistant wound isolates [24,34]. Synergism between linalool-rich EOs and conventional antibiotics may be attributed, at least in part, to the membrane permeabilization activity of EOs, resulting in an enhanced penetration of antibiotics inside the cell [24].…”