Natural Essential Oils as Promising Antimicrobial Agents to Improve Food Safety: Mechanistic Insights Against Multidrug-Resistant Campylobacter jejuni and Campylobacter coli Isolated from Tunisia

The increasing prevalence of multidrug-resistant (MDR) <i>Campylobacter</i> species poses a serious threat to food safety and public health, highlighting the urgent need for natural antimicrobial alternatives to conventional antibiotics. This study investigated the antibacterial potential and mechanism of action of seven essential oils (EOs), <i>Cymbopogon citratus</i>, <i>Mentha pulegium</i>, <i>Artemisia absinthium</i>, <i>Myrtus communis</i>, <i>Thymus algeriensis</i>, <i>Thymus capitatus</i>, and <i>Eucalyptus globulus</i>, against multidrug-resistant <i>Campylobacter jejuni</i> and <i>Campylobacter coli</i>. The antimicrobial activity was first assessed by the agar disk diffusion and broth microdilution methods to determine inhibition zones, minimum inhibitory concentrations (MICs), and minimum bactericidal concentrations (MBCs). The most active EOs were further evaluated through time-kill kinetics, cell lysis, salt tolerance, and membrane integrity assays to elucidate their bactericidal mechanisms. Results showed that <i>E. globulus</i>, <i>T. algeriensis</i>, and <i>M. communis</i> exhibited the strongest inhibitory effects, particularly against <i>C. jejuni</i>, with MIC values ranging from 3.125% to 6.25%, while <i>C. coli</i> was more resistant. Time-kill and lysis experiments demonstrated rapid bacterial reduction and significant decreases in optical density, indicating cell disruption. Additionally, EO treatments reduced salt tolerance and induced leakage of cytoplasmic materials, confirming membrane damage. Overall, these findings suggest that selected essential oils exert potent antimicrobial effects through membrane disruption and osmotic imbalance, offering promising natural strategies to control <i>MDR Campylobacter</i> in food systems. The application of such bioactive compounds could contribute significantly to improving food quality, extending shelf life, and enhancing food safety.