Antibacterial Effect of 16 Essential Oils and Modulation of mex Efflux Pumps Gene Expression on Multidrug-Resistant Pseudomonas aeruginosa Clinical Isolates: Is Cinnamon a Good Fighter?

Abstract

The purpose of the study was to describe the antimicrobial activity of 16 common essential oils (EOs) on multidrug-resistant (MDR) Pseudomonas aeruginosa clinical isolates, including the determination of the effects on mex efflux pumps gene expression. Seventy-two clinical isolates of P. aeruginosa collected between 2020–2022 were screened for susceptibility to EOs using Kirby–Bauer disk diffusion to identify potential candidates for future alternative therapies. The minimal inhibitory concentration (MIC) was further determined for the EO that proved antibacterial activity following the disk diffusion screening. Positive and negative controls were also used for method validation. Since cinnamon EO exhibited the best antimicrobial activity, it was further used to evaluate its influence on mex A, B, C, E, and X efflux pumps gene expression using real-time RT-PCR. Cinnamon EO inhibited all P. aeruginosa strains, followed by thyme EO (37.5%, n = 27) and lavender EO (12.5%, n = 9). The other EOs were less efficient. The MIC detection showed that cinnamon at a concentration of 0.05% v/v inhibited all MDR P. aeruginosa isolates. Thyme, turmeric, peppermint, basil, clove, and lavender EOs presented various results, most of them having activity at concentrations higher than 12.5% v/v. By studying the activity of cinnamon EO on mex efflux pumps, it was found that mexA and mexB (66.5%) were generally under-expressed. The remarkable results produced using the very low concentrations of cinnamon EO, with 100% antimicrobial activity against multi-, extended-, and pan- drug-resistant (MDR, XDR, PDR) P. aeruginosa clinical isolates, completed with the severe alteration of the RNA messaging system, supports its potential to be used as adjuvant treatment, with impact on therapeutic results.

Lipid nanoparticles based on natural matrices with activity against multidrug resistant bacterial species

“…However, the performance of oregano EO was strain-dependent in relation to P. aeruginosa , once a single strain showed resistance to this EO. Similar result was found for strains of P. aeruginosa , tested under the same conditions, showed different responses to the same EO ( Coseriu et al., 2023 ), corroborating the difficulty to treat this type of infection. Other studies have also showed significant antibacterial properties for cinnamon EO, which inhibited the growth of A. baumannii , P. aeruginosa and K. pneumoniae ( El-Kattan and Allam, 2021 ; Ganić et al., 2022 ; Coseriu et al., 2023 ).…”

“…Similar result was found for strains of P. aeruginosa , tested under the same conditions, showed different responses to the same EO ( Coseriu et al., 2023 ), corroborating the difficulty to treat this type of infection. Other studies have also showed significant antibacterial properties for cinnamon EO, which inhibited the growth of A. baumannii , P. aeruginosa and K. pneumoniae ( El-Kattan and Allam, 2021 ; Ganić et al., 2022 ; Coseriu et al., 2023 ). Furthermore, this EO exhibited higher antibiofilm activity against K. pneumoniae , followed by peppermint EO ( Sarwar et al., 2022 ).…”

“…Such bactericidal effect of EO from the bark was higher than cinnamon leaf, probably due to the presence of Σ-cinnamaldehyde as the main component (85.3%). Furthermore, it was already shown that this EO induced rapid death of P. aeruginosa PAO-1, possibly due to the bacterial cell membrane rupture ( Elcocks et al., 2020 ) and the synergistic action among its bioactive components, affecting gene expression and the activity of bacterial efflux pumps ( Coseriu et al., 2023 ).…”

Antioxidant and Antibacterial Activity of Plant Extracts

“…They found that cinnamon essential oil had the best antibacterial activity, even at very low concentrations, while the activity of thyme, turmeric, peppermint, basil, clove, and lavender essential oils presented variable results. The results obtained using cinnamon essential oil by this team suggest the potential of this product to be used as an adjuvant in the antibacterial treatment of infections produced by multidrug-resistant strains of Pseudomonas aeruginosa [7].…”

Evaluation and analysis of multidrug resistance- and hypervirulence-associated genes in carbapenem-resistant Pseudomonas aeruginosa strains among children in an area of China for five consecutive years

“…Therefore, the deletion or mutation of the gene encoding OprD 2 can reduce drug uptake by P. aeruginosa . The efflux pumps are formed by a combination of OprM , which is found in the outer membrane, with MexA and MexB to form a stable complex at the inner membrane ( Coșeriu et al, 2023 ). The most common efflux pump family in Pseudomonas is the resistance nodulation-division.…”