In Vitro Efficacy of Chitosan Nanoparticles Against Staphylococcus aureus and Klebsiella Spp. Isolates From Bovine Mastitis Milk: Addressing Antibiotic Resistance and Exploring Alternative Treatments

This study evaluates the potential antimicrobial properties of chitosan nanoparticles (CNPs) against extended-spectrum beta-lactamases (ESBLs)-producing bacteria (S. aureus and K. pneumoniae) isolated from mastitic milk samples taken from bovine livestock within the El-Menoufia government. One hundred milk samples were tested using the California Mastitis Test, and the isolated bacteria were identified using traditional and molecular techniques. A scanning electron microscope, a Fourier transform infrared spectrometer (FTIR), and X-ray diffraction were utilized to characterize CNPs. The results show that Klebsiella spp. were found in 48% of clinical mastitis cows and 24% of buffaloes, and in 36% and 20% of subclinical cases, respectively. Staphylococcus spp. were found in 56% of clinical mastitis cows and 32% of buffaloes, and in 44% and 24% of subclinical cases. Antibiogram analysis showed Klebsiella spp. were most sensitive to quinolones (53%) and least to tetracycline (34%),while Staphylococcus spp. showed the highest sensitivity to ofloxacin (43.5%) and ampicillin/sulbactam (41.1%). The distribution of blaTEM gene was observed at 41.8%, followed by blaSHV gene and blaCTX-M gene were 34.8% and 32.5% respectively. K. pneumoniae and S. aureus showed the highest multidrug resistance against the tested antibiotic discs. The CNPs were tested in vitro against isolated bacteria and exhibited inhibition zones ranging from 6 to 12 mm. Transfer electron microscopy (TEM) images showed that CNPs significantly altered cell morphology, leading to bacterial death. Therefore, nanoparticles could be a promising solution for controlling, preventing, and treating bovine mastitis.