What is the most common pathogen responsible for osteoarticular infections in children? The answer often is, “Staphylococcus aureus (S. aureus).” Some astute and studious trainees will add, “Kingella kingae (K. kingae).” K. kingaeis an anaerobic Gram-negative organism that inhabits the upper respiratory tract. Although K. kingae is known to be a pathogen in childhood osteoarticular infections, it’s considered to be substantially less common than S. aureus. However, newer molecular techniques (specifically, polymerase chain reaction [PCR] assays) now allow improved identification of K. kingae in bone, synovial fluid, oropharyngeal mucosa, and peripheral blood.
In this issue of Pediatrics, Samara et al (10.1542/peds.2019-1509) report that after the implementation of a real-time PCR assay for K. kingae at their children’s hospital in Geneva, Switzerland, K. kingae was the most common pathogen identified in the 241 children age 0 to 15 years old with osteoarticular infections. In contrast to the time period prior to implementation of the PCR assay, when only 1 case of K. kingae was identified, in the post-implementation period, K. kingae accounted for 32% of cases overall and 51% of those with a confirmed organism. The highest prevalence was among children age 6 to 48 months.
The increased detection of K. kingae has important implications for empiric antimicrobial treatment of suspected osteoarticular infections and, potentially, for the definitive treatment for the >20% of children who do not have a pathogen identified. Common treatment regimens for osteoarticular infections include antimicrobial agents with activity against community-acquired Methicillin-resistant S. aureus (CA-MRSA) but often not against Gram-negative organisms. Should clinicians regularly use antimicrobial agents with activity against K. kingae for empiric treatment? The fundamental question from this study – one that Samara et al acknowledge – is whether the epidemiology of osteoarticular infections is substantially different in Europe compared with the US? While further investigations in the US are needed to define the optimal antimicrobial treatment regimen, increased implementation and use of PCR assays for K. kingae may be warranted to optimize identification of K. kingae and to allow for more accurate epidemiological data. In the meantime, is K. kingae the new king of osteoarticular infections in children? Maybe not yet, but there is compelling evidence that this organism may at least be a prince ready to fill the throne.