Antimicrobial activity of the interaction between essential oils against resistant Staphylococcus aureus isolates from bovine mastitis

Abstract

The control of bovine mastitis is crucial for the sustainability of dairy production. Phytotherapy emerges as a potential alternative for controlling resistant bacteria and potentially replacing conventional therapies. This study aimed to assess the in vitro antimicrobial effect of the Pelargonium graveolens (GEO) and Thymus vulgaris (TEO) essential oils, as well as the interaction between them against strains of Staphylococcus aureus isolated from bovine mastitis. Eight strains of S. aureus isolated from bovine mastitis and two standard strains of human origin were used. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined using the microdilution method. The interaction between the oils was assessed using the checkerboard method. It was observed that both essential oils exhibited inhibitory effects when evaluated separately; however, TEO demonstrated superior bactericidal efficacy. The combination of both oils resulted in a bactericidal complex with a 99% reduction in the effective concentration of GEO. In conclusion, the TEO/GEO complex may contribute to improved therapeutic efficacy, reducing adverse effects, costs, and bacterial resistance development.