Tropheryma whipplei, Molecular Detection, PCR, Blood
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
As an aid in diagnosis of Whipple disease, especially for identifying inconclusive or suspicious cases
Rapid Polymerase Chain Reaction (PCR)
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Tropheryma whipplei PCR, B
Whipple's Disease Associated Bacillus (Tropheryma whipplei)
Specimen Type Describes the specimen type needed for testing
Whole Blood EDTA
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Preferred: Lavender top (EDTA)
Acceptable: Sterile vial
Specimen Volume: 1 mL
Collection Instructions: Send specimen in original tube.
Additional Information: The high sensitivity of amplification by PCR requires the specimen to be processed in an environment in which contamination of the specimen by Tropheryma whipplei DNA is not likely.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Whole Blood EDTA||Refrigerated (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Whipple disease is a chronic, systemic illness that in the majority of cases involves the small intestine and its lymphatic drainage. The disease primarily affects middle-aged individuals, with a peak incidence in the third and fourth decades. Clinical findings may include malabsorption, chronic diarrhea, abdominal pain, arthralgia, fever, and central nervous system symptoms.
Pathologic changes associated with Whipple disease are distinctive, with diagnosis dependent on histologic examination of biopsy specimens from involved tissues. Electron microscopic or special high-resolution light microscopic examination of the lamina propria of the small intestine of patients with untreated Whipple disease patients reveals many rod-shaped bacillary organisms. These tiny bacilli, referred to as Whipple bacilli, measure about 0.25 micrometer long and are seen as periodic acid-Schiff-positive granules within macrophages. These inclusions represent fragments of the cell walls from degenerating bacilli.
Culture of Whipple bacilli from biopsy material is laborious and the organism is very slow growing. Definitive identification of the Whipple-associated bacillus has been difficult because of these limitations. Recently, molecular techniques using PCR and nucleotide sequencing allowed classification of this bacillus as an actinomycete not closely related to any other known species, which has been named Tropheryma whipplei.
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.
A positive result is considered diagnostic of Whipple disease.
A negative result does not negate the presence of the organism or active disease, as false negative results may occur due to inhibition of PCR, sequence variability underlying the primers and/or probes or the presence of Tropheryma whipplei 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 and not be considered diagnostic in themselves. 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.
(Clinical pathologic correlative studies) 321 clinical specimens (including blood, tissue, cerebrospinal fluid, and synovial fluid) were evaluated for the presence of Tropheryma whipplei DNA by targeting the heat shock protein 65 gene using the LightCycler Whip assay and results were compared to those of a conventional PCR assay. The sensitivity and specificity of the LightCycler Whip assay compared to conventional PCR were 98% and 99%, respectively. The analytical sensitivity was less than 50 targets per reaction. The LightCycler Whip showed no cross reaction when tested on a panel of 28 organism genotypically closely related to Tropheryma whipplei by BLAST analysis.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Ramzan NN, Loftus E Jr, Burgart LJ, et al: Diagnosis and monitoring of Whipple disease by polymerase chain reaction. Ann Intern Med 1997;126:520-527
2. Morgenegg S, Dutly F, Altwegg M: Cloning and sequencing of a part of the heat shock protein 65 gene (hsp65) of "Tropheryma whippleii " and its use for detection of "T. whipplei" in clinical specimens by PCR. J Clin Microbiol 2000;38:2248-2253
3. Sloan LM, Rosenblatt JE, Cockerill FR 3rd. Detection of Tropheryma whipplei DNA in clinical specimens by LightCycler real-time PCR. J Clin Microobiol. 2005;43:3516-8
4. von Herbay A, Ditton HJ, Schuhmacher F, et al: Whipple's disease: staging and monitoring by cytology and polymerase chain reaction analysis of cerebrospinal fluid. Gastroenterology 1997;113(2):434-441
Method Description Describes how the test is performed and provides a method-specific reference
Nucleic acid is extracted from all specimens using the MagNA Pure extraction system. The resulting nucleic acid is tested for the presence of the target DNA of Tropheryma whipplei using the LightCycler real-time PCR. The instrument amplifies and continuously monitors the development of target nucleic acid using fluorescent resonance emission technology (FRET) after each cycle. Analysis of the PCR amplification and probe melting curves is accomplished through the use of the LightCycler software.(Sloan LM, Rosenblatt JE, Cockerill FR III: Detection of Tropheryma whipplei DNA in clinical specimens by LightCycler real-time PCR. J Clin Microobiol 2005;43:3516-8)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday, Wednesday, Friday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|