Evaluation of Therapeutic Efficacy of Copper Nanoparticles in Staphylococcus aureus-Induced Rat Mastitis Model

Abstract

The current study was devised to develop alternative, nonantibiotic, and economically viable treatments for bovine mastitis. The concentration of 6.25 μg/mL (25 nm) CuNPs was selected as intramammary (IM) treatment in S. aureus-induced mastitis in rats as this concentration showed a significant zone of inhibition through the in vitro sensitivity test and minimal cell toxicity on fibroblast cell lines. After, this in vivo study was conducted, and rats were divided into four groups of 6 rats each: group I (healthy control/deionized water), group II (disease control), group III (CuNPs), and group IV (gentamicin). Injection of gentamicin IM for 5 days was selected on the basis of an antibiotic sensitivity test. The therapeutic efficacy of CuNPs was assessed on the basis of clinical signs, mammary gland architecture, bacterial load, oxidative stress parameters, and histopathology of mammary glands. The clinical signs of mastitis in group III ameliorated within 3 days of treatment while in group IV clinical signs ameliorated within 4 days of initiation of treatment. On the 5th day after randomization, bacterial load, mammary gland weights, TOS (Total Oxidant Status), and OSI (oxidative stress index) were significantly lower in the CuNPs group compared to the disease control group and commercial antibiotic group. Similarly, TAS of group III was significantly higher compared to that of groups II and IV indicating that CuNPs have better ameliorative efficacy in mastitis. Treatment with IM, CuNPs @ 6.25 μg/mL showed early recovery, reduced bacterial loads, and amelioration of oxidative stress indices henceforth resulting in marked amelioration in histopathological changes compared to rats in group IV. From this study, it may be concluded that CuNPs may provide a potential alternative therapeutic regimen for the treatment of bovine mastitis.