Kingella kingae: An Emerging Pediatric Pathogen

8. Conclusions

As the result of routine drawing of blood cultures from young febrile children, use of the blood culture vial method for culturing synovial fl uid exudates, and development of nucleic acid amplifi cation essays, K. kingae is being increasingly recognized as an important cause of bacteremia and skeletal system infections below the age of 2 years. Kingella kingae is carried in the pharynx by asymptomatic children and is transmitted from child-to-child in young daycare center attendees among whom the organism may cause outbreaks of invasive disease. Concomitant nonspecifi c viral infections and stomatitis appear to facilitate penetration of K. kingae into the bloodstream, resulting in occult bacteremia and seeding of the organism to joints, bones, intervertebral disks, endocardium and other remotes sites. Maternal antibodies appear to protect from respiratory colonization and invasive infections during the fi rst 6 months of life. Fading of vertically-transmitted immunity results in a high prevalence of the organism in the pharynx and increased incidence of bacteremia and skeletal system infections between the ages of 6 months and 2 years. Induction of immunity by prolonged carriage results in low incidence of invasive infections in older children.

The clinical presentation of the disease is often subtle and acute phase reactants are frequently within normal limits, emphasizing the need for a high index of clinical suspicion, drawing blood cultures in young children with joint or bone complaints even in the absence of fever, and inoculation of exudates into blood culture bottles. With the exception of endocarditis, K. kingae infections usually run a benign clinical course and promptly respond to antibiotic therapy and especially to ß-lactam drugs, leaving no long-term sequelae.