Phenotypic and Genotypic Comparison of Antimicrobial-Resistant Variants of <i>Escherichia coli</i> and <i>Salmonella</i> Typhimurium Isolated from Evolution Assays with Antibiotics or Commercial Products Based on Essential Oils

• Main Authors: Natalia Merino (Author), Daniel Berdejo (Author), Elisa Pagán (Author), Claire Girard (Author), Sylvain Kerros (Author), Eleonora Spinozzi (Author), Rafael Pagán (Author), Diego García-Gonzalo (Author)
• Format: Book
• Published: MDPI AG, 2023-10-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/ph16101443; 1424-8247
• Keywords: commercial essential oils; amoxicillin; colistin; <i>Escherichia coli</i>; <i>Salmonella enterica</i> typhimurium; evolution assays; Medicine; R; Pharmacy and materia medica; RS1-441
• Source: Pharmaceuticals, Vol 16, Iss 10, p 1443 (2023)

On account of the widespread development and propagation of antimicrobial-resistant (AMR) bacteria, essential oils (EOs) have emerged as potential alternatives to antibiotics. However, as already observed for antibiotics, recent studies have raised concerns regarding the potential emergence of resistant variants (RVs) to EOs. In this study, we assessed the emergence of RVs in <i>Escherichia coli</i> and <i>Salmonella enterica</i> Typhimurium after evolution assays under extended exposure to subinhibitory doses of two commercial EOs (AEN and COLIFIT) as well as to two antibiotics (amoxicillin and colistin). Phenotypic characterization of RVs from evolution assays with commercial EOs yielded no relevant increases in the minimum inhibitory concentration (MIC) of <i>E. coli</i> and did not even modify MIC values in <i>S</i>. Typhimurium. Conversely, RVs of <i>E. coli</i> and <i>S</i>. Typhimurium isolated from evolution assays with antibiotics showed increased resistance. Genotypic analysis demonstrated that resistance to commercial EOs was associated with enhanced protection against oxidative stress and redirection of cell energy toward efflux activity, while resistance to antibiotics was primarily linked to modifications in the cell binding sites of antibiotics. These findings suggest that AEN and COLIFIT could serve as safe alternatives to antibiotics in combating the emergence and dissemination of antimicrobial resistance within the agrifood system.