Bone and joint infections caused by Kingella kingae: six cases and review of the literature.

Six cases of Kingella kingae arthritis, osteomyelitis, and diskitis were studied, and data were reviewed from an additional 23 cases in the English-language literature. K. kingae is a slow-growing, fastidious, gram-negative microorganism that colonizes mucous membranes of the upper respiratory tract. Infections were predominantly seen in infants and young children (86% of cases) and were preceded by an upper respiratory tract infection in 31% of patients. Low-grade fever (38 degrees C-39 degrees C) and pain or swelling involving the affected limb developed insidiously. However, 76% of the infections were diagnosed within 1 week after the onset of symptoms. The knee was involved in 47% and the hip in 33% of cases of arthritis. Osteomyelitis mainly involved the femur (36%); four cases of osteomyelitis (29%) were diagnosed as diskitis. The erythrocyte sedimentation rate was greater than 20 mm/h in all patients. Gram stains of aspiration fluid were positive in 19% of cases, whereas blood cultures yielded growth in only 5%. Radiographic signs indicating the presence of osteomyelitis were observed in 93% of patients. All patients recovered completely. K. kingae is an important causative agent in indolent bone, joint, and intervertebral disk infections.