Comparative Evaluation of the Inhibitory Effect of Some Essential Oils with Antibiotics against Pseudomonas aeruginosa

Abstract

Gas chromatography/mass spectroscopy analysis was performed to identify the chemical components of three extracted essential oils including thyme, marjoram, and sage. The antibacterial activity of the extracted essential oils againstPseudomonas aeruginosa(ATCC 9027) was investigated using disc diffusion assay, either alone or in combination with standard antibiotics (piperacillin, cefepime, meropenem, gentamicin, and norfloxacin). Results showed that the studied oils exhibited a variety of activities against the tested bacterium. Thyme oil was the most active followed by marjoram oil, whereas sage displayed no activity towards the tested organism. Thyme oil enhanced the antibacterial activity of cell wall targeting antibiotics (piperacillin, cefepime, and meropenem) by more than twofold. Marjoram oil potentiated the activity of all the tested antibiotics except norfloxacin. Sage, despite its inactivity againstpseudomonas, synergistically enhanced the activity of piperacillin, meropenem, and gentamicin. Thyme essential oil, containing thymol as a major component (33.6%), exhibited higher activity alone or in combination with antibiotics than marjoram which contained alcoholic terpenes or sage essential oil that contained 1,8-cineole as its major component (29%). The investigated oils, as natural bioactive agents, may be used to enhance the activity of antibiotics towardspseudomonas.

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

“…Weaker synergistic effects have been detected for sage ( Salvia officinalis L., Lamiaceae) EO in combination with piperacillin, meropenem and gentamicin. 1,8-Cineole (29%) ( Figure 1 ) was the major oxygenated terpene in sage EO [ 101 ]. Alecrim pimento ( Lippia sidoides Cham .…”

“…Monoterpene alcohols, such as 4-terpineol, also have antipseudomonal activity, as they inhibit the microbial oxygen uptake and oxidative phosphorylation. Terpenoid ethers (1,8-cineole) have a lower capacity to sensitize the pathogen to the antibiotic activity as they lack free hydroxyl groups, a structural feature present in both phenolic and alcoholic terpenoids [ 101 , 105 ]. Three Thymus saturejoides Coss.…”

Essential Oil and Hydrophilic Antibiotic Co-Encapsulation in Multiple Lipid Nanoparticles: Proof of Concept and In Vitro Activity against Pseudomonas aeruginosa

“…An antagonistic effect has been observed for the combinations of sage ( Salvia officinalis ) EO and FEP against P. aeruginosa ATCC 9027, where 1,8-cineole (29%) was the major oxygenated terpene [ 61 ]. Terpenoid ethers, such as 1,8-cineole, have been formerly reported to achieve a lower capacity to sensitize pathogens to antibiotic activity as they lack free hydroxyl groups, a structural feature present in both phenolic and alcoholic terpenoids [ 61 , 62 ]. Nevertheless, REO showed a synergistic effect in combination with aminoglycoside antibiotics against E. coli [ 60 ].…”

Preventing male infertility by marjoram and sage essential oils through modulating testicular lipid accumulation and androgens biosynthesis disruption in a rat model of dietary obesity

“…Marjoram oil extract is a rich source of terpenoids, as thymol, carvacrol [66], terpinen-4-ol, a-terpinene and g-terpinene [67]. Among these, the monoterpenoid carvacrol was appointed as an activator of PPARa and g. An effect that may be related to the observation that carvacrol supplementation to HFD-fed mice tended to reduce body weight gain, visceral fats and plasma lipids compared with mice fed HFD, probably through regulating adipose tissue genes expression and proteins associated with the signaling cascades that lead to adipogenesis [68].…”