Primary pyomyositis is a bacterial infection of skeletal muscle first recognized in tropical regions of the world but needing characterization in temperate climates.

This population-based study used the Healthcare Utilization Project/Nationwide Inpatient Sample database to characterize the trends of pyomyositis admissions in the United States from 2002–2014 using ICD-9 diagnostic codes.

We found a concerning more than three-fold increase in the incident pyomyositis admissions over our study period. The median length of stay was over twice as long compared to other hospitalized patients. Patients with pyomyositis were younger and more likely to be male and Black. There were more cases in the West and South compared to Midwest and Northeast. Age-adjusted odds ratios revealed significant association of pyomyositis with HIV, types 1 and 2 diabetes mellitus, hematologic malignancy, organ transplant, malnutrition, chronic kidney disease, obesity, and rheumatoid arthritis. The most commonly identified bacterial diagnosis was Staphylococcus aureus. Pseudomonas species were the most commonly identified gram-negative bacteria.

This nationwide review of pyomyositis in the United States suggests a concerning increase in incidence and provides information on the trends, demographics, risk factors, and causative organisms for pyomyositis in the United States.