Evaluation of Antimicrobial and Antibiofilm Activity of Eucalyptus urograndis (Clone I144) Pyroligneous Extract on Bovine Mastitis Isolate of Multiple-Drug-Resistant Staphylococcus aureus Strains.

Milk is an important agricultural product and is consumed worldwide. However, the dairy sector faces a significant challenge due to bovine mastitis, a common disease that has a substantial impact on the dairy industry. In more severe cases, it leads to the culling of chronically infected cows. Mastitis poses a risk due to the frequent use of antibiotics in treatment, which contributes to the spread of bacteria with antimicrobial resistance. The present study aimed to evaluate the antimicrobial and antibiofilm potential of a pyroligneous extract of Eucalyptus urograndis (clone I144) against multidrug-resistant Staphylococcus aureus, the causative agent of mastitis. Sensitivity profiles to various conventional antibiotics were assessed, including the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC), and biofilm inhibition, in ten Staphylococcus aureus strains using the crystal violet method. The results showed that the multidrug-resistant strains were sensitive to the pyroligneous extract of Eucalyptus urograndis (clone I144) at a concentration of 12.5% and exhibited antibiofilm activity starting at a concentration of 3.13%. In conclusion, our findings show that the pyroligneous extract of Eucalyptus urograndis (clone I144), at 12.5%, inhibited different multidrug-resistant S. aureus and MRSA strains isolated from bovine mastitis. These results indicate that the extract represents an effective preventive strategy against mastitis-causing pathogens that are difficult to treat, making it a promising alternative to reduce the dependence on synthetic antibiotics. In vivo studies are needed to confirm these findings and provide a basis for evidence-based clinical guidelines.