Kingella kingae infections: a review and a presentation of data from 10 Swedish cases

Kingella kingae is a fastidious gram-negative rod related to the Neisseriae. Together with data from published cases of K. kingae infection, we report the clinical and laboratory findings from 10 cases in western Sweden; a specific serological reaction is also described. The diagnoses were osteomyelitis, septic arthritis, discitis, endocarditis, occult bacteraemia and phlegmon. The data from the Swedish cases, together with those from previous reports in the literature provided the basis for an analysis of a total of 33 cases, ranging from self-limiting to potentially fatal infections. In orthopaedic infections (n = 19), including 3 cases of discitis, the course was usually protracted but subacute and benign, although the full-blown, acute septic arthritis was also encountered. Endocarditis (n = 10) was characterized by a stormy clinical course and the development of significant sequelae. The majority of the patients were previously healthy children. 42% of them had a current or recent upper respiratory tract infection. After start of antibiotic treatment patients were afebrile within a few days. Betalactam antibiotics should be regarded as the drugs of choice for coping with K. kingae. We stress the insidious course of skeletal infections in children and urge the importance of early puncture of a suspected focus to establish a correct diagnosis without delay. The clinical data suggest that K. kingae should be regarded as a significant pathogen.