Rapid Screening of Essential Oils as Substances Which Enhance Antibiotic Activity Using a Modified Well Diffusion Method

Abstract

Antimicrobial resistance is recognized as one of the major global health challenges of the 21st century. Synergistic combinations for antimicrobial therapies can be a good strategy for the treatment of multidrug resistant infections. We examined the ability of a group of 29 plant essential oils as substances which enhance the antibiotic activity. We used a modified well diffusion method to establish a high-throughput screening method for easy and rapid identification of high-level enhancement combinations against bacteria. We found that 25 essential oils possessed antibacterial activity against Escherichia Coli ATCC 25922 and methicillin-resistant Staphylococcus aureus (MRSA) 43300 with MICs that ranged from 0.01% to 2.5% v/v. We examined 319 (11 × 29) combinations in a checkerboard assay with E. Coli ATCC 25922 and MRSA 43300, and the result showed that high-level enhancement combinations were 48 and 44, low-level enhancement combinations were 214 and 211, and no effects combinations were 57 and 64, respectively. For further verification we randomly chose six combinations that included orange and Petitgrain essential oils in a standard time-killing assay. The results are in great agreement with those of the well diffusion assays. Therefore, the modified diffusion method was a rapid and effective method to screen high-level enhancement combinations of antibiotics and essential oils.

Antibacterial activity and synergistic antibiotic mechanism of trialdehyde phloroglucinol against methicillin‐resistant Staphylococcus aureus

“…Cui et al (2021) revealed that 25 essential oils possessed antibacterial activity against MRSA. Orange and petitgrain essential oils showed significant synergistic effects with amikacin against Salmonella typhimurium and Klebsiella pneumoniae .…”

“…The corresponding values for NPG and penicillin were 1.98-log 10 CFU ml À1 and 2.09-log 10 CFU ml À1 , respectively. As described in the literature (Cui et al, 2021;G omara & Ram on-García, 2019), a synergistic antibacterial effect is a ≥ 2-log 10 CFU ml À1 reduction compared with the most active individual drug. For ATCC 43300, the combination of TPG and penicillin showed a strong synergistic effect, with a decrease of 5.21 log 10 CFU ml À1 (TPG) to 7.13 log 10 CFU ml À1 (penicillin) (Figure 3).…”

“…combinations (TPG or NPG plus bacitracin or penicillin) showed highlevel synergistic antibacterial effects against ATCC 43300, while three combinations (TPG plus bacitracin, NPG plus PG, and TPG plus PG) showed strong synergistic effects against AD3. The detailed antibacterial effects of phenolic compounds and antibacterial agents against MRSA strains are shown in the TableS1 Cui et al (2021). revealed that 25 essential oils possessed antibacterial activity against MRSA.…”

Synthesis of Chitosan-Based Gold Nanoparticles: Antimicrobial and Wound-Healing Activities

“…The antibacterial potential of synthesized Chi/AuNPs was determined by agar well diffusion assay against the tested selected bacterial strains [ 46 ]. All bacteria examined had a density of 0.5 McFarland at turbidity.…”

Epidemiology and Control of Nosocomial Pathogens Recovered from Some Governmental Hospitals, Cairo, Egypt

“…According to, Clinical & Laboratory Standards Institute (CLSI) guidelines (Cui et al, 2021) muller Hinton agar plates were inoculated with the tested organisms using a sterile cotton swab rolled in the suspension of bacterial and/or fungal cultures. A sterile cork borer of 5mm diameter was used to make wells on inoculated medium.…”