Pyomyositis is caused by which of the following?

Pyomyositis is an acute bacterial infection of the skeletal muscle caused by Staphylococcus aureus. It may be primary or secondary to a penetrating injury or contiguous anatomic infection. It typically affects the major muscles of the lower extremity and the gluteal muscles. Patients usually presents with pain, tenderness and edema of the involved muscle group. Abscess can develop in the muscle groups. Diagnosis is confirmed by needle aspiration or operative incision and drainage. Treatment involves adequate drainage along with antibiotic therapy against Staphylococcus aureus. In contrast to necrotizing soft tissue infections, pyomyositis is characterized by a localized infectious process, conventional purulence, lack of surrounding tissue necrosis and a ourable response to simple incision drainage. Ref: Skeletal Muscle: Pathology, Diagnosis and Management of Disease edited by Victor R. Preedy, page 313.