Pathogenesis of Kingella kingae Infections

The real-time PCR assay targeting the toxin-encoding rtxB gene was employed to assess the bacterial load of asymptomatic pharyngeal carriers and children in whom the diagnosis of Kingella kingae arthritis or osteomyelitis was confirmed by a positive PCR test performed in blood, synovial fluid, or bone exudates. K. kingae has been traditionally considered exquisitely susceptible to antibiotics, and beta-lactamase production has been rarely described. The dynamics of carriage of respiratory bacteria can be studied in longitudinal surveys in which the population is repeatedly sampled over a prolonged period of time and isolates are analyzed by highly discriminative methods. K. kingae is usually highly susceptible to penicillins and cephalosporins, and beta-lactamase production has been rarely reported in invasive isolates, although its prevalence shows wide geographic differences. Early surgical interventions have been necessary for life threatening complications unresponsive to medical therapy and the overall mortality rate is unusually high.