Article in Japanese

A case of MRSA infective endocarditis complicated with polyarthritis and multiple dermatoid lesions in a child with no underlying disease

Kyosuke IZUMI^1）, Kenichi OKUMURA^1）, Takuma SUGAHARA^1）, Kento ITOI^1）, Kumpei SEKINE^1）, Yuko AMIMOTO^1）, Takuzo WADA^1）, Motokazu NISHIKADO^1）, Ikuyo ARAI^1）, Hitoshi AWAGUNI^1）, Mayumi NAGASAWA^1）, Jun SHINOZUKA^1）

In infective endocarditis, complication as polyarthritis was very rale. We report a case of infective endocarditis caused by methicillin-resistant Staphylococcus aureus （MRSA）, in which complicated with polyarthritis and multiple skin lesions.
Case: A 5-year-old boy presented to a local clinic with a 3-day history of fever and a painful skin rash on his lower limbs. Blood tests revealed an increased inflammatory response; thus, the patient was admitted to our hospital. On the first day of hospitalization, empirical antibiotic therapy with cefazolin sodium was initiated, following the collection of blood cultures. By the second day, blood cultures returned positive, and the FilmArray blood culture identification panel confirmed the presence of MRSA. A cardiac ultrasound revealed mild mitral regurgitation, leading to the diagnosis of infective endocarditis. Magnetic resonance image revealed fluid accumulation around the knee and hip joint. MRSA was detected in the specimen collected from the Janeway lesion. Vancomycin was administered for 4 weeks after the blood culture was negative, and the patient was discharged on the 35th day of hospitalization without complications. There was no report concerning about infective endocarditis complicated with polyarthritis, especially in a child case.

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1）Department of Pediatrics, Uji Tokushukai Hospital

Key words	infective endocarditis, methicillin-resistant Staphylococcus aureus, polyarthritis, Janeway lesion, Osler node
Received	July 29, 2025
Accepted	November 10, 2025

37 (4)：317─325,2025