The paper describes the case of a 14-year-old girl with intense right shoulder pain and severe signs of local and systemic inflammation. Magnetic resonance imaging revealed a pyomyositis of right shoulder girdle muscles. Blood culture was found positive for methicillin-resistant Staphylococcus aureus (MRSA) and the chest computed tomography scan revealed nodular infiltrates in both pulmonary fields resulting from septic embolism. A prolonged antibiotic therapy according to antibiogram allowed the complete recovery.
Pyomyositis is a deep pyogenic infection of the skeletal muscle tissue and is most commonly caused by Staphylococcus aureus species. In the described case, repetitive trauma due to karate may have caused the initial muscle cell damage with subsequent haematoma, which subsequently becomes colonised by bacteria during a transient bacteraemia. There is an increasing prevalence of pyomyositis in temperate climates and in the last few years MRSA has emerged as a pathogen within the community (CA-MRSA) also in healthy people. An early diagnosis is important to avoid local and systemic complications.