Aiding in the diagnosis of Coxiella burnetii infection (eg, Q fever) using tissue specimens
For more information see Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology
Q fever
C. burnetii
Coxiella burnetii
For more information see Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology
Varies
Specimen source is required.
Question ID | Description | Answers |
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SRCQF | Specimen Source |
The high sensitivity of amplification by polymerase chain reaction requires the specimen to be processed in an environment in which contamination of the specimen by Coxiella burnetii DNA is unlikely.
Submit only 1 of the following specimens:
Specimen Type: Fresh tissue or biopsy
Sources: Lung, bone, liver, 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:
1. Collect fresh tissue specimen.
2. Submit tissue only, do not add fluid to tissue
3. Refrigerate or freeze specimen.
Specimen Stability Information: Refrigerated (preferred) <7 days/ Frozen <7 days
Preferred Paraffin-embedded tissue block:
Specimen Type: Formalin-fixed, paraffin-embedded tissue block (FFPE)
Sources: Lung, bone, liver, heart valve, aorta, or endocardium
Supplies: Tissue Block Container (T553)
Container/Tube: Tissue block
Collection Instructions: Submit a formalin-fixed, paraffin-embedded tissue block to be cut and returned.
Specimen Stability Information: Ambient (preferred)/Refrigerated
Acceptable Paraffin-embedded tissue block:
Specimen Type: Formalin-fixed, paraffin-embedded tissue block (FFPE)
Sources: Lung, bone, liver, heart valve, aorta, or endocardium
Container/Tube: Sterile container for each individual cut section (scroll).
Collection Instructions: Perform microtomy and prepare 5 separate 10-micron sections. Each section (scroll) must be placed in a separate sterile container for submission.
Specimen Stability Information: Ambient (preferred)/Refrigerated
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.
Fresh tissue or biopsy: 5 mm(3)
Paraffin-embedded tissue block: two 10-micron sections
Tissue in formalin formaldehyde, or acetone Bone marrow Decalcified bone Unstained slides | Reject |
Specimen Type | Temperature | Time | Special Container |
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Varies | Varies |
Aiding in the diagnosis of Coxiella burnetii infection (eg, Q fever) using tissue specimens
For more information see Infective Endocarditis: Diagnostic Testing for Identification of Microbiological Etiology
Coxiella burnetii, the causative agent of Q fever, is a small obligate intracellular bacterium associated with animals. Acquired through aerosol exposure, it generally causes mild respiratory disease. A small number of acute cases advance to a chronic infection, which typically manifests as endocarditis. Left untreated, Q fever endocarditis may be fatal. Serologic and histopathologic studies may be nonspecific and subjective, respectively, limiting usefulness for patient diagnosis.
Evaluation of infected tissue, blood, or serum using polymerase chain reaction (PCR) may be a useful tool for diagnosing some cases of C burnetii infection. Mayo Clinic Laboratories has developed a real-time PCR test that rapidly detects C burnetii DNA in clinical specimens by targeting a sequence of the shikimate dehydrogenase gene (aroE) unique to C burnetii.
Not applicable
A positive result indicates the presence of Coxiella burnetii DNA.
A negative result indicates the absence of detectable C burnetii DNA, but it does not negate the presence of the organism and may occur due to inhibition of polymerase chain reaction, sequence variability underlying primers or probes, or the presence of C burnetii DNA in quantities less than the limit of detection of the assay.
Test results should be used as an aid in diagnosis and not be considered diagnostic in themselves. A 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 was clinically validated in a blinded manner using 52 archived, formalin-fixed, paraffin-embedded heart valve specimens from patients with endocarditis. A single sample determined to contain polymerase chain reaction (PCR) inhibitors was omitted from the final analysis set. Compared with existing diagnostic data, PCR had a sensitivity of 100% (8/8) and specificity of 100% (43/43). All samples were assayed with a second PCR assay targeting the IS1111 element.(1) Complete concordance was noted between the 2 assays (P >0.999). The limit of detection of the assay is 216 targets/mcL for fresh tissue and estimated (by Probit analysis) to be 9.7 targets/mcL in formalin-fixed paraffin-embedded tissue.
1. Frangoulidis D, Meyer H, Kahlhofer C, Splettstoesser WD: 'Real-time' PCR-based detection of Coxiella burnetii using conventional techniques. FEMS Immunol Med Microbiol 2012 Feb;64(1):134-136.
2. Liesman RM, Pritt BS, Maleszewski JJ, Patel R. Laboratory diagnosis of infective endocarditis. J Clin Microbiol. 2017 Sep;55(9):2599-2608. doi: 10.1128/jcm.00635-17.
3. Kersh GJ, Bleeker-Rovers CP: Coxiella: Evaluation, interpretation, and reporting results. In: Carroll K, Pfaller M, eds. Manual of Clinical Microbiology. 12th ed. ASM Press; 2019:1185-1186.
4. Anderson A, Bijlmer H, Fournier PE, et al: Diagnosis and management of Q fever-United States, 2013: recommendations from CDC and the Q Fever Working Group. MMWR Recomm Rep 2013;62(RR-03):1-30.
Bacterial nucleic acid is extracted from the specimen using the automated MagNA Pure instrument. The purified DNA is placed on the LightCycler instrument, which amplifies and monitors by fluorescence the development of target nucleic sequences after each PCR cycle. A specific target sequence from Coxiella burnetii is amplified and the resulting segment is detected using specific hybridization probes. Detection of the C burnetii target is performed through melting curve analysis using the LightCycler software.(Cockerill FR, Uhl FR: Applications and challenges of real-time PCR for the clinical microbiology laboratory. In: Reischl U, Wittwer C, Cockerill F, eds. Rapid Cycle Real-Time PCR, 2002:3-27; Kersh GJ, Bleeker-Rovers CP: Coxiella. In: Carroll K, Pfaller M, eds. Manual of Clinical Microbiology. 12th ed. ASM Press; 2019:1180-1188)
Monday through Friday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
87798
Test Id | Test Order Name | Order LOINC Value |
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CBRP | Coxiella burnetii (Q fever) PCR | 90442-5 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
SRCQF | Specimen Source | 31208-2 |
62193 | Coxiella burnetii PCR | 90442-5 |