Citrobacter freundii: a newly reported cause of pyomyositis.

Pyomyositis has been uncommonly reported in temperature climates, but is being recognized with increasing frequency. The most common etiologic agent is Staphylococcus aureus, although other pathogens have been rarely implicated. The authors describe the first case of pyomyositis caused by Citrobacter freundii. Because of the rarity of this disease in North America, it is often initially misdiagnosed. Neuromuscular sonography, a non-invasive imaging technique, identified the muscle abscess in this patient.