Gram-negative bacterial pyomyositis: unique case and review

Bacterial pyomyositis in tropical or temperate climates is usually associated with gram-positive organisms, and Staphylococcus aureus has been recovered most often. In contrast, skeletal muscle infection due to aerobic gram-negative bacteria is an acknowledged rarity, even in tropical areas. A literature review revealed only five organisms implicated in gram-negative pyomyositis in the United States; to this list, we add a unique case of pyomyositis caused by Serratia marcescens that occurred in a patient with multiple myeloma. Although the data are limited, it appears that lower leg muscles are more likely to be involved and that clinical cure is often achieved following appropriate drainage and antibiotic therapy.