Bacterial myositis

Bacterial myositis, also known as infective myositis or pyomyositis, is a rare infectious condition characterized by bacterial infection of skeletal muscle tissue. It can range from a diffuse inflammatory process (infectious myositis) to a localized abscess formation within the muscle (pyomyositis). The condition primarily affects the musculoskeletal system and can involve any skeletal muscle group, though large muscle groups such as the quadriceps, gluteal muscles, and iliopsoas are most commonly affected. Key symptoms include localized muscle pain, swelling, tenderness, fever, and sometimes overlying skin erythema. In severe cases, the infection can progress to sepsis, a life-threatening systemic inflammatory response. Bacterial myositis is most frequently caused by Staphylococcus aureus, including methicillin-resistant strains (MRSA), though other organisms such as Streptococcus species, Escherichia coli, and anaerobic bacteria may also be responsible. Risk factors include immunocompromised states (such as HIV/AIDS, diabetes mellitus, or immunosuppressive therapy), trauma, intravenous drug use, and concurrent infections. The condition is more commonly reported in tropical regions (tropical pyomyositis) but can occur worldwide. Diagnosis typically involves a combination of clinical assessment, laboratory findings (elevated inflammatory markers such as CRP and white blood cell count), blood cultures, and imaging studies including MRI, which is the most sensitive modality for detecting muscle inflammation and abscess formation. Treatment consists of targeted antibiotic therapy based on culture and sensitivity results, along with surgical drainage of any abscess collections when present. Early recognition and treatment are essential to prevent complications such as compartment syndrome, septicemia, and multiorgan failure. With appropriate management, the prognosis is generally favorable, though delayed diagnosis can lead to significant morbidity.

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