Display omitted •Nix/SiO2 co-doped NiAl(1-x)CoFe2O4 were prepared by sol–gel and calcined at 650 °C.•Ni increasing increases the saturation magnetization and the optical energy gap.•Excellent antibacterial activity against all studied nosocomial strains was noted.•The nanocomposites release massive amounts of bacterial proteins.•The nanocomposites can delay wound healing. Among the most dangerous concerns for public health is a nosocomial bacterial infection of burn wounds. Nanocomposites with strong antibacterial activity have developed as a feasible candidate for these potential infects. Nix/SiO2co-doped NiAl(1-x)CoFe2O4nanocrystallites (sampled S0-S3) were prepared through the sol–gel method and calcined at 650 °C.Direct and/or indirect transition can be experienced in the prepared nanocrystallites with increased probability of direct type. Both the direct and indirect transition energy increase with Ni content increase.Further, the antibacterial activity against four nosocomial pathogens was evaluated through analysis of zone of inhibition, minimum inhibitory concentration (MIC), and some physiological changes. The S3 nanocomposites revealed excellent antibacterial activity against all studied nosocomial strains. Besides, it prevents bacterial growth and releases massive amounts of bacterial proteins compared to the others. Results demonstrated that it can fight nosocomial pathogens, especially those that infect the wounds and delay wound healing.