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Test Code KKRP Kingella kingae, Molecular Detection, PCR

Useful For

Aids in diagnosing Kingella kingae infection

Method Name

Real-Time Polymerase Chain Reaction (PCR)

Reporting Name

Kingella kingae PCR

Specimen Type

Varies


Necessary Information


Specimen source is required.



Specimen Required


The high sensitivity of amplification by PCR requires the specimen to be processed in an environment in which contamination of the specimen by Kingella kingae DNA is unlikely.

 

Submit only 1 of the following specimens:

 

Specimen Type: Synovial fluid

Preferred: Lavender top (EDTA)

Acceptable: Pink top (EDTA), royal blue top (EDTA), sterile vial containing EDTA-derived aliquot, red clot tube (no anticoagulant), or sterile container

Specimen Volume: 0.5 mL

Collection Instructions: Send specimen in original tube (preferred).

Specimen Stability Information: Refrigerated (preferred) <7 days /Frozen <7 days

 

Specimen Type: Fresh tissue or biopsy

Sources: Bone, joint, synovium, heart valve, aorta, or endocardium

Container/Tube: Sterile container

Specimen Volume: Entire collection or 5 mm(3)- approximately the size of a pencil eraser

Collection Instructions: Collect fresh tissue specimen.

Specimen Stability Information: Refrigerated (preferred) <7 days/ Frozen <7 days

 

Supplies: Tissue Block Container (T553)

Specimen Type: Formalin-fixed, paraffin-embedded tissue block

Sources: Bone, joint, synovium, heart valve, aorta, or endocardium

Container/Tube: Sterile container for cut sections or Tissue Block Container (T553)

Specimen Volume: Submit formalin-fixed paraffin-embedded tissue block to be cut and returned. Alternately, perform cuts and place two to five 10-micron sections in a sterile container for submission (minimum volume: two 10-micron sections).

Specimen Stability Information: Ambient (preferred)/Refrigerated


Specimen Minimum Volume

Fluid: 0.5 mL
Tissue: 5 mm(3) or two 10-micron sections

Specimen Stability Information

Specimen Type Temperature Time
Varies Varies

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

Tissue in formalin, formaldehyde, or acetone; anticoagulants other than EDTA, green top (heparin) tube, blue top (citrate) tube, yellow top (ACD) tube, serum separator tube (SST); bone marrow; slides

Clinical Information

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 cardiac, bone, joint tissue, or fluid by PCR is a useful tool for the diagnosis of some cases of K kingae infection.

Reference Values

Not applicable

Interpretation

A positive test is strongly suggestive of Kingella kingae infection.

 

A negative test indicates the absence of detectable K kingae DNA, but does not negate the presence of the organism or recent disease and may occur due to sequence variability underlying primers and probes, or the presence of K kingae in quantities below the limit of detection of the assay.

Cautions

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 samples and 10-negative samples for each accepted sample type; fresh tissue, formalin-fixed paraffin-embedded tissue (FFPE), synovial fluid, and EDTA blood. No PCR inhibition was 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 fresh tissue and FFPE was 73.7 CFU/mcL. The LoD of synovial fluid was 1.3 CFU/mcL.

Clinical Reference

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

Method Description

Nucleic acid is extracted from the specimen using the automated MagNA Pure instrument. Target specific primers are used to amplify the rxtB gene region of Kingella kingae; amplification is monitored by detecting fluorescence produced by target-specific FRET hybridization probes. This real-time PCR reaction takes place on a LightCycler instrument. Detection of the K kingae target is performed through melting curve analysis using the LightCycler software.(Cockerill FR, Uhl JR: Applications and challenges of real-time PCR for the clinical microbiology laboratory. In Rapid Cycle Real-Time PCR Methods and Applications. Edited by U Reischl, C Wittwer, F Cockerill. Berlin, Germany, Springer-Verlag, 2002, pp 3-27)

Day(s) and Time(s) Performed

Varies; Batched 3 times per week

Analytic Time

2 days

Specimen Retention Time

1 week

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

87798

LOINC Code Information

Test ID Test Order Name Order LOINC Value
KKRP Kingella kingae PCR 65809-6

 

Result ID Test Result Name Result LOINC Value
KKSRC Specimen Source 31208-2
48324 Kingella kingae PCR 65809-6