Kingella kingae: A Pediatric Pathogen of Increasing Importance

As the result of the use of blood culture vials for seeding joint and bone exudates, and nucleic acid amplification methods, Kingella kingae is emerging as an important pathogen in patients <3 years of age. The organism is carried asymptomatically in the oropharynx of young children, coinciding with the age of increased attack rate of invasive disease, and propagates through close personal contact. Carriage of K. kingae is a dynamic process with frequent turnover of strains after weeks or months of continuous or intermittent colonization. Colonizing K. kingae enters the bloodstream through breaches in the respiratory mucosa and disseminates to bones, joints, or the endocardium. Daycare attendance increases the risk for K. kingae acquisition and transmission, and outbreaks of invasive disease have been reported among children in daycare. The most common manifestations of K. kingae disease in children are skeletal system infections (in 56% of patients), bacteremia (in 39%), pneumonia (in 4%), and endocarditis (in 1%). The clinical presentation is often subtle and laboratory tests are frequently normal, requiring a high index of suspicion. The organism is susceptible to most antibiotics, and with the exception of cases of endocarditis, invasive K. kingae infections usually run a benign uncomplicated clinical course.