Rapid bedside diagnosis of occult pyomyositis using point-of-care ultrasound in a patient with sepsis of unknown origin

Pyomyositis is a rare bacterial infection of skeletal muscle characterised by abscess formation, having significant morbidity. Early diagnosis is often challenging, especially in patients with atypical presentations. We report a case of pyomyositis in an immunocompetent adult male, promptly diagnosed using point-of-care ultrasound (POCUS) in the emergency department. The patient presented with fever, hypotension and confusion, and no source of infection was initially identified. Careful re-examination revealed subtle thigh asymmetry and tenderness. POCUS revealed an intramuscular collection in the left thigh and a diagnosis of pyomyositis was confirmed by ultrasound-guided aspiration and culture. Culture of the purulent fluid grew <i>Escherichia coli</i>, an unusual pathogen in pyomyositis, particularly in immunocompetent individuals. Rapid diagnosis enabled timely drainage and culture-directed antibiotic therapy, leading to complete recovery. This case underscores the importance of repeated clinical assessment and highlights the role of bedside ultrasound in rapidly identifying occult sources of sepsis, particularly when advanced imaging is delayed.