Non-Tropical Pyomyositis Caused by Methicillin-Resistant Staphylococcus aureus: An Unusual Cause of Bilateral Leg Pain

Background: Pyomyositis (PM) is a primary suppurative infection of skeletal muscles that was originally described as a tropical disease and is now being seen with increasing frequency in temperate regions. Although PM is classically described as a disease of young, healthy individuals, its incidence is increasing in immunocompromised patients, particularly those with human immunodeficiency virus infection. Staphylococcus aureus is the etiologic agent in the majority of cases of PM worldwide, with methicillin-resistant Staphylococcus aureus (MRSA) being reported with increasing frequency. Mortality from PM is as high as 10%, and complications include metastatic abscesses, septicemia, and shock. Early signs and symptoms of PM are usually subtle and may be easily overlooked or misdiagnosed as a more benign condition. Case Report: A case of non-tropical PM due to MRSA in a young man is presented. This is followed by a review of the epidemiology, clinical findings, pathophysiology, diagnosis, differential diagnosis, treatment, and prognosis of this challenging and unusual condition. Conclusion: Because PM presents with subtle symptoms that are easily misunderstood as signs of more common and more benign conditions, it is often missed early in its course. By recognizing PM early in its course, it is possible to treat it before surgical drainage is required and before complications develop.