Reduced Susceptibility of Typhimurium Strains to Oregano Essential Oil and Enrofloxacin: An Assay.

Several European animal nutrition companies have incorporated essential oils (EOs) into animal feed as a result of the prohibition of antibiotics to promote animal growth. Previous studies of EOs have highlighted the absence of bacterial resistance for these substances, although most of the published works focus on studying their tolerance to subinhibitory doses. For this study, oregano essential oil (OEO) was chosen for its proven inhibitory and bactericidal activity.

Susceptibility Distribution to Essential Oils of Salmonella enterica Strains Involved in Animal and Public Health and Comparison of the Typhimurium and Enteritidis Serotypes.

To determine the distribution of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of essential oils (EOs) of cinnamon (Cinnamomum zeylanicum), clove (Eugenia caryophyllata), oregano (Origanum vulgare), common thyme (Thymus vulgaris), and red thyme (Thymus zygis) against Salmonella enterica, double serial dilutions of each EO were challenged with 85 Salmonella strains belonging to 23 serotypes of animal origin. The results showed the bactericidal character of the EOs tested against S. enterica, highlighting the oregano with MIC and MBC of 3.

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

The inhibitory potential by contact and vapor of basil, cinnamon, clove, peppermint, oregano, rosemary, common thyme, and red thyme essential oils (EOs) against 20 strains of Streptococcus suis was determined by the disk diffusion test. The broth microdilution method was used to determine the minimal inhibitory and minimal bactericidal concentration (MIC and MBC) of the four selected oils. Furthermore, the bactericidal power (ratio MBC/MIC) was calculated.

Combination of Antimicrobials and Essential Oils as an Alternative for the Control of Salmonella enterica Multiresistant Strains Related to Foodborne Disease.

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.