IN VITRO EVALUATION OF STAR ANISE (ILLICIUM VERUM) AGAINST PATHOGENIC STRAINS OF STAPHYLOCOCCUS AUREUS ISOLATED FROM CLINICAL CASES OF BOVINE MASTITIS

Abstract

Bovine mastitis is a common and economically damaging disease in dairy farming. This mammary gland infection can impact the reproductive performance of farm animals. Among the agents that cause mastitis, bacteria are responsible for approximately 90% of cases, with Staphylococcus aureus standing out, which is present in dairy herds with a prevalence of 30 to 85%. For bacterial control, various strategies and antimicrobials are tested and developed for applicability and resolution of the problem. However, certain challenges exist, such as bacterial resistance, toxicity (when applied to feed or animal skin), and high financial costs, which minimize efficacy and often render it unviable. In this context, alternative substances of natural origin are sought. Given this scenario, the objective of this study was to investigate star anise essential oil (Illicium verum) as an antibacterial agent against mastitis-causing S. aureus isolated from dairy herds in western Santa Catarina. The essential oil was purchased commercially and tested against four strains of S. aureus isolated from milk samples of cows with clinical and subclinical mastitis. Disk diffusion and planktonic cell quantification (CFU/mL) tests were performed to test antibacterial activity. Although the results of the disk diffusion tests did not demonstrate significant inhibitory zones, there was a reduction in colony-forming units, with two bacterial strains being reduced by 100%. The results demonstrate that the use of essential oil is promising in controlling mastitis caused by S. aureus.

DOI: https://doi.org/10.56238/edimpacto2025.025-005