ANTIMICROBIAL ACTIVITY OF CHITOSAN NANOPARTICLES AGAINST STAPHYLOCOCCUS AUREUS ISOLATED FROM MASTITIC MILK

Bovine mastitis caused by Staphylococcus aureus (S. aureus) is a major concern in the dairy industry, leading to economic losses and potential public health risks. The emergence of antibiotic-resistant S. aureus strains necessitates the development of alternative therapeutic strategies. This study investigates the antimicrobial activity of chitosan nanoparticles (CNPs) against S. aureus isolated from mastitic milk samples. CNPs were prepared using the ionic gelation method and characterized for size and surface charge by dynamic light scattering (DLS), and zeta potential analysis. Their antibacterial activity was evaluated using the agar well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. The effect was also explored through morphological observations in scanning electron microscopy (SEM). CNPs exhibited significant antibacterial activity against S. aureus in agar well diffusion, with MIC and MBC values 40 μg/mL and 80 μg/mL, respectively. In CNP-treated cells, SEM images revealed surface disruptions and deformations. These findings suggest that CNPs disrupt the S. aureus membrane, leading to cell death.