A Fatal Case of Disseminated Infection Caused by Community-Associated Methicillin-Resistant Staphylococcus aureus USA300 Clone.

Methicillin-resistant Staphylococcus aureus (MRSA) USA300 is a representative community-associated MRSA (CA-MRSA) clone worldwide. Herein, we report the case of a patient with USA300 clone infection who could not be salvaged. A 25-year-old man who had sex with men presented with symptoms including fever persisting for one week and skin lesions located on the buttocks. Computed tomography imaging showed multiple nodules and consolidations, especially in the peripheral lung fields, right iliac vein thrombosis, and pyogenic myositis of medial thighs bilaterally. Blood cultures revealed MRSA bacteremia. The patient's condition deteriorated rapidly, complicated by acute respiratory distress syndrome and infective endocarditis. Despite the intubation on the 6th hospital day, he died on the 9th day. Multilocus sequence typing of this patient's MRSA strain revealed sequence type 8 with a staphylococcal cassette chromosome of mec type IVa, Panton-Valentine leukocidin gene, and the arginine catabolic mobile element, indicating presence of the USA300 clone. Patients with CA-MRSA skin lesions presenting with furuncles or carbuncles on the lower body are at a higher risk of severe disease. The patient's background, appearance, and location of skin lesions are critical for the early diagnosis of severe CA-MRSA infection.