Diagnosing Kingella kingae infections in infants and young children

Introduction: Kingella kingae is currently recognized as the prime etiology of skeletal system infections in children aged 6–48 months. The organism is notoriously fastidious, its growth is inhibited by synovial fluid and bone exudates, and its presence in clinical specimens is commonly missed by traditional culture methods. Areas covered: The present review discusses the use of improved laboratory methods to detect the organism in normally sterile body fluids, exudates, and upper respiratory tract specimens. Expert commentary: While inoculation of joint and bone exudates into blood culture vials dilutes the concentration of detrimental factors and significantly improves the isolation of the organism, novel PCR-based assays have enhanced sensitivity, shortened the time-to-detection of K. kingae from 3–4 days to <24 h, and enabled the bacteriological diagnosis in patients being administered antibiotic therapy. PCR-based assays that amplify the 16S rRNA gene results in a 200% improvement in the diagnosis of the organism compared to culture, whereas the use of real-time PCR tests that target K. kingae-specific DNA sequences increases the detection rate by a five-fold factor and reduces the fraction of culture-negative septic arthritis and osteomyelitis in infants and young children.