Staphylococcal pyomyositis in a temperate region: epidemiology and modern management

OBJECTIVES: To describe all cases of staphylococcal pyomyositis in the Geelong region of Victoria over 110 months, to estimate the incidence of this disease, and to describe the clinical outcomes and identify any predisposing factors. DESIGN, PARTICIPANTS AND SETTING: A prospective case series identified by clinical features (local pain and fever) and magnetic resonance imaging (MRI) findings (hyperintense signal on T2-weighted scan), among patients presenting to Geelong Hospital, Victoria between 1 April 1998 and 1 June 2007. MAIN OUTCOME MEASURES: Estimation of incidence, clinical course and identification of predisposing factors. RESULTS: We estimate an annual incidence of 0.5 cases per 100 000 person-years, and propose a recent history of vigorous exercise (six of 11 patients) and underlying skin condition (five of 11 patients) as possible predisposing factors. MRI showed eight patients had osteomyelitis and one had septic arthritis. All patients had bacteraemia and one had mitral valve endocarditis. The duration of intravenous antibiotic therapy varied between 4 and 12 weeks, and all patients were completely cured. CONCLUSION: Pyomyositis should be considered in patients presenting with local pain, fever, muscle tenderness, and a recent history of vigorous exercise or underlying skin condition. MRI may guide non-surgical management.