(555) Nonendemic Pyomyositis Management in an Immunocompetent United States Marine

Introduction: Tropical Pyomyositis (TP) is a rare skeletal muscle infection commonly caused by S. Aureus (SA), normally seen in tropical countries among immunocompromised children or young adults. Diagnosis of TP in the United States is rare and complicated by its ambiguous initial symptomatology, leading to mismanagement, undertreatment, and increased risk of morbidity and mortality of patients that lack TP in the differential.

Description: A 47-year-old male without past medical or travel history was transferred to our ICU with persistent SA bacteremia without endocarditis complicated by multiple musculature and prostatic abscesses, septic emboli, cavitary pneumonia (PNA), and septic renal vein thrombosis. The patient's initial presentation two weeks prior was for URI-like symptoms with fever and pronounced muscle aches that had failed two rounds of community acquired antibiotic regimens. He was diagnosed with multi-lobar PNA that quickly evolved into an acidosis and renal injury in the setting of rhabdomyolysis and SA bacteremia. An expansive work-up of infectious diseases, autoimmune diseases, vasculitis, and malignancies with multiple rounds of echocardiograms, MRIs, CTs, and consults between 9 medical services without initial source identification was pursued. The patient received 8 different antibiotics while subspecialists debated the origin. 15 days into his ICU stay, whole-body imaging showed hypodense collections within multiple muscles, including lower extremities as well as the iliac, gluteal, and iliopsoas muscles, the site of his muscle aches starting one month prior. These were drained by IR and surgery and the patient was diagnosed with stage 2 pyomyositis. The patient recovered after a prolonged course of Oxacillin with lasting urologic and musculature complications.

Discussion: Although uncommon in the U.S., pyomyositis can be a deadly missed diagnosis. Mortality rates are low in in endemic countries, around 1-4%, with developed healthcare systems, but in underdeveloped or non-endemic regions rates increase. Critical care providers should consider adding TP to their differential list, limiting both imaging as well as unnecessary exposure to broad spectrum antibiotics, while attaining accelerated surgical intervention for source control.