Article in Japanese

A case of osteoarthritis caused by group B streptococcus in a 9-year-old boy

Kenta OCHAI ^1）, Kenichi TAKANO^1）

A 9-year-old boy with no medical history complained of fever and right hip and buttock pain on the day before his hospitalization. On the day of hospitalization, he was unable to move due to the pain and was taken to the emergency room. His temperature was 39.4℃. He had tenderness in the right hip and buttock. There was restriction of motion of the right hip joint and no history of trauma. Blood tests showed a white blood count (WBC) of 20100/L (Neut 91.8%) and C-reactive protein (CRP) of 4.00mg/dL. Hip echocardiography and magnetic resonance imaging (MRI) of both hips were normal. He was admitted to the hospital and treated with cefazolin because severe osteoarthritis could not be ruled out. On hospital day 2, Streptococcus agalactiae (GBS) was detected in blood culture and the antibiotics was changed to ampicillin. On hospital day 5, MRI of both hips showed high signal areas in the right sciatic and pubic bone and increased right hip joint fluid. The patient was diagnosed bacteremia and osteoarthritis due to GBS. In cases of acute onset fever and arthralgia, severe osteoarthritis, including pyogenic osteomyelitis, should be considered, even if there is no abnormality on early imaging. Invasive GBS infections have been reported primarily in neonates and infants. Although they are extremely rare in school children with no medical history, it is important to recognize them as severe infections.

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1）Children’s Medical Center, Kitakyushu City Yahata Hospital

Key words	invasive group B streptococcal infection, osteoarthritis, pediatric
Received	December 22, 2020
Accepted	June 15, 2021

33 (3)：256─262,2021