Nowadays, several pathogenic strains of bacteria and fungi have become resistant against many therapeutic drugs. Therefore, using novel biologically synthesized nanomaterials as antimicrobial drugs against the human pathogens is of great concern. Consequently, here, the study was aimed to assess the antimicrobial activity of titanium dioxide nanoparticles (TiO2NPs) phycosynthesized from Spirulina platensis and some conventional antifungal (clotrimazole, itraconazole, ketoconazole, micconazole, and nystatin) and antibacterial (amoxicillin and gentamicin) drugs against both Candida parapsilosis and Prototheca ciferrii. The TiO2NPs-and clotrimazole-induced ultrastructure changes on the microbes using transmission electron microscope were also investigated. The TiO2NPs significantly inhibited the growth of C. parapsilosis. The clotrimazole and ketoconazole showed the highest inhibitory effect against …