Green synthesis of CuO nanoparticles using thyme extract and their application as cephalexin carriers against <i>Klebsiella pneumoniae</i>

Cephalexin is commonly used to treat various bacterial infections. Given the escalating issue of antibiotic resistance worldwide and the need for alternative treatment methods, this study focused on enhancing the antimicrobial efficacy of cephalexin against pneumonia, which remains a major cause of mortality among children. <i>Klebsiella pneumoniae</i> strains were isolated from pneumonia patients. Wild thyme extract was used in the synthesis of environmentally friendly copper oxide nanoparticles, which were characterized using advanced analytical techniques. Cephalexin was loaded onto these nanoparticles to evaluate their enhanced antibacterial efficacy against <i>Klebsiella pneumoniae</i>. In addition, comprehensive studies were conducted on the antioxidant properties and anti-biofilm capabilities of the newly synthesized cephalexin-CuO nanocomposite. UV-visible spectroscopy, X-ray diffraction, and magnetic resonance confirmed the successful binding of cephalexin to the synthesized nanoparticles. The bioactivity and antioxidant evaluations also revealed promising results. The antibacterial activity test showed that the copper nanoparticles exhibited a minimum inhibitory concentration (MIC) in the range of 1.8-2.2 mg ml^-1, indicating enhanced efficacy of the nanocomposite. Moreover, the cephalexin-copper oxide nanocomposite achieved complete bacterial inhibition at an optimal concentration of 30 mg ml^-1, while biofilm formation inhibition tests identified 20 mg ml^-1 as the optimal concentration for suppression of pulmonary biofilm generation by <i>Klebsiella pneumoniae</i>. These findings underscore the potential of the cephalexin-CuO nanocomposite as a promising candidate for the development of innovative antibacterial and antioxidant solutions.