LAUSR

Simple Summary Bacterial infections are among the widely disturbing diseases and leading cause of mortality around the world. Some bacterial strains can invade the skeletal muscles by producing proteolytic enzymes, causing pyomyositis. The aim of the present investigation was to evaluate ZnO nanoparticles (ZnO-NPs) as an effective treatment for bacterial pyomyositis in combination with a physiotherapeutic program (consisting of swimming and a low-level laser treatment (LLLT)). Results revealed the significant and synergistic effect of both ZnO-NPs along with the physiotherapeutic program in enhancing the histoarchitecture, immunity and hemostasis, and some vital physiological biomarkers. This emphasizes the urgency of spreading more awareness about the importance of the combined effect between nanotechnology and physiotherapeutic programs in muscle regeneration after pyomyositis caused by virulent infection with proteolytic bacteria. Abstract Myositis tropicans or pyomyositis is a muscle inflammation resulting from a bacterial infection of skeletal muscle (commonly caused by Staphylococcus aureus) that usually leads to hematogenous muscle seeding. The present study was designed to estimate the role of ZnO-NPs and a physiotherapeutic program in the management of induced biceps femoris atrophy in rats through histological, biochemical, and radiological examinations at different time intervals. At the beginning, several bacterial strains were evaluated through a proteolytic enzyme activity assay and the highest activity was recorded with the Staphylococcus aureus strain. ZnO-NPs were synthesized with the arc discharge method with an average size of 19.4 nm. The antibacterial activity of ZnO-NPs was investigated and it was revealed that the prepared ZnO-NPs showed a minimum inhibitory concentration of 8 µg/mL against the tested bacterium. The cytotoxicity of the prepared ZnO-NPs was tested in C2C12 myoblast cells, and it was elaborated that CC50 was 344.16 µg/mL. Biceps femoris pyomyositis was induced with a potent strain (Staphylococcus aureus); then, a physiotherapeutic program combined with the prepared ZnO-NPs treatment protocol was applied and evaluated. The combined program claimed antibacterial properties, preventing muscle atrophy, and resulted in the most comparable value of muscle mass.