Nayhara M. Guimarães

Antimicrobial resistance poses a significant challenge in human and veterinary medicine, primarily due to the overuse and misuse of antimicrobial agents. This issue is especially problematic when treating bovine mastitis, a prevalent infection in dairy cattle often caused by Staphylococcus aureus. We developed a sterile emulsion incorporating essential oils (EOs) of Origanum vulgare and Thymus vulgaris, known for their antimicrobial properties. The formulation based on poloxamer 407 was designed for intramammary or topical application on bovine teats. The most promising emulsion was subjected to preliminary stability testing at various temperature conditions over a 35-day period, during which its physicochemical characteristics, texture profile, and film-forming capacity were assessed. In vitro assays were used to evaluate its efficacy against both antimicrobial-sensitive and -resistant S. aureus strains. Thymol was identified as the predominant bioactive compound in the EOs. The formulation, containing 10% (w/w) EOs, exhibited antimicrobial activity against all tested strains and remained stable without phase separation. The emulsion demonstrated film-forming properties along with a satisfactory texture profile. These findings suggest that the emulsion has potential as an alternative therapeutic approach for the treatment of antimicrobial-resistant S. aureus infections in bovine mastitis, highlighting the potential of natural compounds in combating AMR. Further clinical studies are necessary to confirm the safety and therapeutic efficacy of the emulsion in vivo.