Combination of Antimicrobials and Essential Oils as an Alternative for the Control ofSalmonella entericaMultiresistant Strains Related to Foodborne Disease

Abstract

Due to the increase in bacterial resistance to antimicrobials (AMBs) commonly used in veterinary and human medicine, the new strategies for controlling zoonoses focus on the study of natural products with demonstrated AMB activity, such as essential oils (EOs). The aim of this study was to evaluate the in vitro effect of the combination of enrofloxacin (ENR), ceftiofur (CEF), and trimethoprim-sulfamethoxazole (SXT) with cinnamon, clove, oregano, and red thyme EOs against multiple drug-resistant strains of Salmonella enterica. The minimum inhibitory concentration (MIC) of each product was determined by microdilution and "Checkerboard" methods and their combined effect was evaluated against 15 strains of S. enterica. The results were interpreted by the calculation of fractional inhibitory concentration (FIC) and their respective indexes (FICI). Significant susceptibility of all strains to the four EOs was observed. The results showed a synergistic effect between EOs and AMBs tested, highlighting the upper percentage of total synergies of the SXT with the four EOs (FICI ≤0.5 in 60% of assays), and the most effective combination being the one of ENR and cinnamon. The MIC of cinnamon was reduced from 1250 to 312.5 μg/mL and the MIC of ENR from 2 to 0.031 μg/mL. There was no antagonism in the tested combinations (AMBs-EOs). Our results support the combined use of EOs and AMBs for the control of multiresistant strains of S. enterica with a reduction of the minimum effective dose of AMBs and their adverse effects.

Antimicrobial activity of selected essential oils against Streptococcus suis isolated from pigs

“…However, the nontoxic concentration of cinnamon that they publish was lower than our values. Several studies have shown synergistic effect between the essential oils tested in this work and some traditional antimicrobials, with a notable decrease in the effective concentration (Solarte et al., ).…”

“…However, the nontoxic concentration of cinnamon that they publish was lower than our values. Several studies have shown synergistic effect between the essential oils tested in this work and some traditional antimicrobials, with a notable decrease in the effective concentration (Solarte et al, 2017). In vivo studies in pigs with oregano, thyme, and cinnamon generally describe a significant increase in growth performance without altering the quality of the carcass (Namkung et al, 2004;Simitzis, Symeon, Charismiadou, Bizelis, & Deligeorgis, 2010), which is associated with a beneficial effect on the intestinal microbiota, nutrient absorption, and on the action of digestive enzymes (Zeng, Zhang, Wang, & Piao, 2015).…”

Trans-Cinnamaldehyde and Eugenol Increase Acinetobacter baumannii Sensitivity to Beta-Lactam Antibiotics

“…A recent study also reported synergistic effect of Eucalyptus camaldulensis with polymyxin B against MDR Acinetobacter baumannii ( Knezevic et al, 2016 ). In another study, Enrofloxacin and cinnamon were observed to possess synergistic effect against Salmonella enterica ( Solarte et al, 2017 ). Further, extracts of medicinal plant Holarrhena antidysenterica with Conessine increased susceptibility of extensively drug resistant A. baumannii to novobiocin and rifampicin ( Siriyong et al, 2016 ).…”

Combined effect of conventional antimicrobials with essential oils and their main components against resistant Streptococcus suis strains

“…The combination of oxytetracycline with cinnamon resulted in synergy for 2/5 strains, and additive for 3/5 strains, this interaction has also been observed in previous studies with Salmonella enterica , an important foodborne pathogen (Bassole and Juliani ; Solarte et al . ). The combination of penicillin (Fig.…”