Abstract
Background: Bovine subclinical mastitis is a significant disease that significantly impacts the health of dairy cows and subsequently affects milk production. Among the various causes of subclinical mastitis, bacterial infections, particularly Staphylococcus aureus (S. aureus), play a crucial role. Aim: The aim of this investigation was to isolate and identify S. aureus strains from cows with subclinical mastitis, assess their antimicrobial susceptibility, virulence genes, and investigate the potential antibacterial activity of Moringa oleifera ethanolic extract and Selenium (Se) nanoparticles against both somatic cell count (SCC) and S. aureus count in subclinical mastitic cows. Methods: We collected 110 milk samples from dairy cows with subclinical mastitis in the Kafrelsheikh governorate before treatment with intramammary antibiotics. Samples were identified using pH detection, SCC at ≤200,000 cells/ ml, and California Mastitis Test. Results: The effect of M. oleifera ethanolic extract, Se nanoparticles, and Ciprofloxacin antibiotic in reducing SCC and S. aureus counts was significant. Selenium nanoparticles and Ciprofloxacin antibiotics showed the highest reduction in the S. aureus count, comparable to M. oleifera ethanolic extract, while ciprofloxacin followed by M. oleifera ethanolic extract, and Selenium nanoparticles were effective against somatic cell count. Conclusion: This study emphasizes the widespread occurrence of S. aureus in subclinical bovine mastitis and highlights the potential of M. oleifera ethanolic extract and Se nanoparticles as promising treatment options. Selenium nanoparticles demonstrated notable antibacterial effects against S. aureus and contributed to a reduction in somatic cell counts. Considering these findings, we propose additional studies on the potential of Selenium nanoparticles as antibacterial agents, as they demonstrate effectiveness in preventing and managing S. aureus subclinical mastitis.