Synergistic Action of AMX Associated with 1,8-Cineole and Its Effect on the ESBL Enzymatic Resistance Mechanism

Abstract

The purpose of the present study is twofold. First, it aims to evaluate the synergistic action of the ß-lactam antibiotic; AMX is associated with 1,8-cineole on six clinical isolates of ESBL-producing Escherichia coli and Klebsiella pneumoniae strains. Second, it aims to determine the effect this association has on the ESBL enzymatic resistance mechanism. The synergistic action of AMX/1,8-cineole was evaluated using partial inhibitory concentrations (PIC), determined by a microplate, a checkerboard and time–kill assays. The effect of AMX/1,8-cineole associations on the ESBL enzymatic resistance mechanism was evaluated using a new optimized enzymatic assay. This assay was based on the determination of the AMX antibacterial activity when combined with 1,8-cineole (at subinhibitory concentrations) in the presence or absence of the ß-lactamase enzyme toward a sensitive E. coli strain. The results of both checkerboard and time–kill assays showed a strong synergistic action between AMX and 1,8-cineole. The results of the enzymatic assay showed that the combination of AMX with 1,8-cineole notably influences the enzymatic resistance of the reaction by decreasing the affinity of the β-lactam antibiotic, AMX, to the β-lactamase enzyme. All obtained results suggested that the AMX/1,8-cineole association could be employed in therapy to overcome bacterial resistance to AMX while reducing the prevalence of resistance.

The Combination of Amoxicillin and 1,8-Cineole Improves the Bioavailability and the Therapeutic Effect of Amoxicillin in a Rabbit Model

“…This increase in biological activity in the test group could be explained by an improvement in the bioavailability of the antibiotic through interactions with 1,8-cineole thereby increasing its intestinal absorption and diffusion across the blood–brain barrier (BBB). This can be also explained by the fact that the association of AMX and 1,8-cineole protects the antibiotic by considerably decreasing ß-lactam’s affinity for ß-lactamase, as we previously demonstrated with the enzymatic assay [ 21 ]. Thus, AMX recognition changes in the presence of 1,8-cineole according to these results.…”

“…Therefore, finding an alternative, urgently needed, and effective drug to overcome the diverse bacterial infections seems to be crucial. The aim of the present research paper was designed to verify if the synergistic effect of the AMX/Clav and 1,8-cineole combination obtained in vitro [ 21 ] would be reflected in vivo in the rabbit model. A rabbit was more adequate for the performance of the present experiments than mice and rats, because the size of the rabbit allowed us to recover sufficient quantities of physiological fluids to test the antimicrobial activity of the drugs using a microtechnique.…”

“…A rabbit was more adequate for the performance of the present experiments than mice and rats, because the size of the rabbit allowed us to recover sufficient quantities of physiological fluids to test the antimicrobial activity of the drugs using a microtechnique. Results from our previous in vitro findings demonstrated that the addition of 1,8-cineole significantly increased the antibacterial activity of AMX [ 21 ]. Previous research data revealed that 1,8-cineole was a strong active compound against many pathogenic strains, including Escherichia coli , Staphylococcus aureus, Pseudomonas aeruginosa , and Bacillus subtilis [ 30 , 31 ].…”

“…Thus, the search for an alternative strategy with greater efficacy is an urgent medical need. Several studies have investigated the use of antibiotics in combination with major essential oil (EO) compounds [ 16 , 17 , 18 , 19 , 20 , 21 ]. They have revealed that this approach could be efficiently used in therapy to overcome any resistance to antibiotics.…”

“…Nowadays, some researchers reported that essential oils have the capacity to act as resistance modifying agents and thereby enhance the efficacy of antibiotics [ 20 ]. Based on these facts and on our previous studies [ 16 , 21 ] of the combination of AMX with 1,8-cineole EO, a major compound used to combat ESBL bacterial resistance, we have conducted an in vivo experiment to study the pharmacokinetics and pharmacodynamics of AMX combined with 1,8-cineole using a rabbit model.…”