Primary Bacterial Pyomyositis in Children: A Systematic Review

Background: Tropical pyomyositis has had a recent increase in the United States, Europe, and other nontropical areas. The purpose of this study was to provide an accurate description of the demographics, presenting features, sites of involvement, microbiology, imaging modalities, medical and surgical management, complications, and predictors of clinical course. Methods: We searched PubMed, Cochrane, Web of Science Collection, Scopus, and Embase databases yielding 156 studies. Of these, 23 articles were selected for statistical analysis. Results: The average age at presentation was 8.4±1.9 years with males more commonly affected. Fever, painful limp, and localized pain were the most common presenting symptoms. Pelvis, lower extremity, trunk and spine, in descending order, were the most commonly affected locations. Iliopsoas, obturator musculature, and gluteus musculature were the most commonly affected muscle groups. The mean time to diagnosis was 6.6±3.05 days. Staphylococcus aureus was the most common offending organism. The mean length of hospital stay was 12.0±4.6 days. Medical management alone was successful in 40% of cases (143/361) with an average duration of 9.5±4.0 and 22.7±7.2 days of intravenous and oral antibiotics, respectively. Surgical management consisted of open drainage in 91.3% (199/218) or percutaneous drainage in 8.7% (19/218) of cases. Painful limp, fever, and larger values of white cell count and erythrocyte sedimentation rate were associated with an increased need for surgery. Obturator and calf muscle involvement were strongly associated with multifocal involvement. There were 42 complications in 41 patients (11.3%). Methicillin-resistant S. aureus was associated with an increased risk of complications. The most common complications were osteomyelitis, septicemia, and septic arthritis. Conclusions: Primary pyomyositis should be considered in cases suggesting pediatric infection. Magnetic resonance imaging is the most commonly used imaging modality; however, ultrasound is useful given its accessibility and low cost. Medical management alone can be successful, but surgical treatment is often needed. The prognosis is favorable. Early diagnosis, appropriate medical management, and potential surgical drainage are required for effective treatment. Level of Evidence: Level IV - systematic review.