Test Catalog

Test ID: KKBRP    
Kingella kingae, Molecular Detection, PCR, Blood

Useful For Suggests clinical disorders or settings where the test may be helpful

Aiding in the diagnosis of Kingella kingae infection using whole blood specimens

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Kingella kingae is a fastidious short Gram-negative bacillus that may colonize the oropharynx of young children. Colonization may occasionally lead to invasive disease via hematogenous dissemination, primarily in children younger than 4 years of age. This most commonly results in bone and joint infection; K kingae is the most frequent cause of osteomyelitis and septic arthritis in children aged 6 to 36 months. K kingae may also cause endocarditis, involving both native and prosthetic valves, in patients of any age and is considered part of the HACEK (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) group of organisms, known for causing culture-negative endocarditis. K kingae produces a repeat-in-toxin (RTX) toxin.


Diagnosis of K kingae infection may be challenging due to the fastidious nature of the organism in culture. Evaluation of blood by PCR is a useful tool for the diagnosis of some cases of K kingae infection.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Not applicable

Interpretation Provides information to assist in interpretation of the test results

A positive result indicates the presence of Kingella kingae DNA.


A negative result indicates the absence of detectable K kingae DNA, but does not negate the presence of the organism and may occur due to inhibition of PCR, sequence variability underlying primers or probes, or the presence of K kingae DNA in quantities less than the limit of detection of the assay.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Test results should be used as an aid in diagnosis. The single assay should not be used as the only criteria to form a clinical conclusion, but results should be correlated with patient symptoms and clinical presentation. A negative result does not negate the presence of the organism or active disease.


This assay does not detect species of Kingella other than kingae or negevensis (see Supportive Data).


This assay cross-reacts with Kingella negevensis.(1)

Supportive Data

This assay was validated by testing 30-spiked positive ETDA whole blood samples and 10-negative samples. No PCR inhibitors were encountered. The assay was 100% sensitive and specific. The assay showed no cross-reactivity when tested with a panel of 67 bacterial isolates, including Kingella species other than kingae. The limit of detection (LoD) in EDTA-whole blood was 1.3 CFU/mcL.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. El Houmami N, Bzdreng J, Durand GA, et al: Molecular tests that target the RTX locus do not distinguish between Kingella kingae and the recently described Kingella negevensis species. J Clin Microbiol 2017;55:3113-3122

2. Murphy TF: In Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Edited by GL Mandell, JE Bennett, R Dolin. Seventh edition. Philadelphia, Churchill Livingstone/Elsevier, 2010, pp 2774-2776

3. Zbinden R: Aggregatibacter, Capnocytophaga, Eikenella, Kingella, Pasteurella, and Other Fastidious or Rarely Encountered Gram-Negative Rods. In Manual of Clinical Microbiology. Edited by JH Jorgensen, KC Carroll, G Funke, MA Pfaller. 11th edition. Washington DC. ASM Press 2015, pp 652-666

4. Yagupsky P: Kingella kingae: carriage, transmission, and disease. Clin Microbiol Rev. 2015 Jan;28(1):54-79

5. Madigan T, Cunningham SA, Ramanan P, et al: Real-Time PCR Assay for Detection of Kingella kingae in Children. J Pediatr Infect Dis 2018;13:216-233