Kingella kingae: From asymptomatic colonization to invasive pediatric infections

As a result of the use of blood culture vials for seeding joint and bone exudates, and the development of nucleic acid amplification methods, Kingella kingae is being increasingly recognized as an emerging invasive pathogen and the most common etiology of septic arthritis in children aged 6-36 months. K. kingae is carried asymptomatically in the pharynx, and is transmitted from child-to-child by close contact between family members and playmates. K. kingae organisms enter the bloodstream through breaches in the respiratory mucosa and disseminate to remote sites. Skeletal system infections are the most common presentations of K. kingae disease, followed by bacteremia, pneumonia and endocarditis. Children with invasive K. kingae infections frequently show a mild clinical picture and normal acute-phase reactants, requiring a high index of suspicion. The organism is usually susceptible to antibiotics and, with the exception of endocarditis cases, most patients promptly respond to adequate antimicrobial therapy with no permanent sequelae.