Antimicrobial Activity of Origanum vulgare L. And Salvia rosmarinus Spenn (syn Rosmarinus officinalis L.) Essential Oil Combinations Against Escherichia coli and Salmonella typhimurium Isolated from Poultry
2025
Federico Toso | Daniel Buldain | Daiana Retta | Paola Di Leo Lira | María Laura Marchetti | Nora Mestorino
The ban on antibiotic growth promoters (AGPs) in poultry farming has prompted the search for effective, natural alternatives. Essential oils (EOs), such as those from oregano (Origanum vulgare: OVEO) and rosemary (Salvia rosmarinus: ROEO), possess antimicrobial and antioxidant properties that may contribute to intestinal health and pathogen control. This study evaluated the antibacterial activity of OVEO and ROEO, individually and combined, against six Escherichia coli and six Salmonella typhimurium strains isolated from healthy poultry via cloacal swabs, as well as E. coli ATCC 25922 and S. typhimurium ATCC 14028 strains. The minimum inhibitory concentrations (MIC) were determined at five pH levels (7.4&ndash:5) simulating avian gastrointestinal tract conditions. EO composition was determined by GC-FID-MS. Checkerboard assays revealed partial or full synergistic effects at most pH, especially under acidic environments (pH &le: 5.5), where the fractional inhibitory concentration (&Sigma:FIC) values often indicated synergy. No antagonistic interactions were observed. These results suggest that OVEO and ROEO combinations are promising candidates to replace AGPs in poultry, particularly because of their enhanced efficacy under gastrointestinal pH. The strategic use of EO blends may reduce pathogen load, support performance, and limit antimicrobial resistance development, suggesting their potential as natural alternatives to AGPs under One Health principles.
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