In vitro and In Vivo Antimicrobial Activity of Melia Azedarach-Mediated Copper Oxide Nanoparticles Against Multidrug-Resistant Klebsiella pneumoniae.

The increasing prevalence of multidrug-resistant pathogens such as Klebsiella pneumoniae, which causes pneumonia and acute respiratory distress syndrome (ARDS) with high mortality rates, poses a significant clinical challenge. Fourth-generation antibiotics, such as cefepime, are often considered the last line of defense against these pathogens. The emergence of cefepime-resistant K. pneumoniae (CRKP) compromises the efficacy of available antibiotics and highlights the importance of new alternative therapies. This study directed the phyto-synthesis of copper oxide (CuO) nanoparticles using Melia azedarach leaf extract and evaluated their antibacterial efficacy, both individually and synergistically with cefepime, against multidrug-resistant Klebsiella pneumoniae through in vitro and in vivo models. The phyto-synthesized copper oxide nanoparticles were characterized using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray analysis (EDAX). The antimicrobial efficacy of phyto-synthesized CuONPs, both alone and in combination with the antibiotic cefepime, was assessed through disk diffusion, minimum inhibitory concentration (MIC) assays, and in vivo experimentation. The phyto-synthesized CuONPs were characterized as crystalline, hexagonal in shape, and less than 30 nm in size. The antimicrobial efficacy was confirmed by inhibition zones ranging from 12 to 14 mm against multidrug-resistant Klebsiella pneumoniae. The CuONPs showed strong antimicrobial activity, with a minimum inhibitory concentration (MIC) of 2.25 µg/mL against the pathogenic strain. In comparison, cefepime alone showed no antimicrobial activity. Notably, when CuONPs were combined with cefepime, a synergistic effect was observed, lowering the MIC to 1.92 µg/mL. This study addresses the in vitro and in vivo analysis of CuONPs, with cefepime exerting a potent synergistic effect against the multidrug-resistant strain Klebsiella pneumoniae. This combined treatment resulted in an 82% inhibition rate, a significant reduction in bacterial burden, improved histopathological profiles, faster wound healing, and a regulated immune response.