Molecular Detection by PCR

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Reference Details

Description:

Molecular detection of Tropheryma whipplei by PCR.

Test Category:
Molecular Detection
Pathogen:
Tropheryma whipplei
Illnesses and Diseases:
  • Whipple's disease
Specimen:

For suspected classic Whipple’s disease (gastroenteritis), acceptable and reliable samples for testing are duodenal, gastric, or colonic biopsies. For suspected neurologic infection, acceptable samples for testing are CSF, brain tissue, and in some rare cases whole blood. Blood has the potential for positive detection but may not be an ideal specimen type due to decreased sensitivity.  Cardiac tissues and lymph nodes are also acceptable specimen types. Send tissues or scrolls in sterile screw top culture bottles/jars. For blood samples, a minimum of 1mL of unspun whole blood in a sealed EDTA collection vial is required. For all other fluids, a minimum of 0.5 mL is required in a sealed screw top tube. Glass slides, serum, plasma, saliva, throat specimens, urine, and stool are not acceptable samples and will not be tested.

Collection Method:

Whole blood unspun in EDTA tubes. Tissues are preferred frozen but formalin fixed/paraffin embedded tissue will also be processed. Blood samples should be received at the NML no longer than 48 hours from the time of collection.

Specimen Processing, Storage and Shipping:

It is preferable that specimens be frozen after collection.  If that’s not possible, then store at refrigeration temperature (2 – 8°C. Ship frozen tissue and CSF samples on dry ice and whole blood on ice packs. If any specimens, including CSF, were not frozen after collection, refrigerate and ship on ice packs.

Transportation of Dangerous Goods:

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

For additional guidance on the transport of infectious substances in other languages, please click on the link below.

http://www.who.int/ihr/capacity-strengthening/infectious-substances/en/

Patient Criteria:

For detection of classic gastrointestinal Whipple’s disease, the patient should exhibit symptoms of weight loss, mal-adsorption, weakness, fatigue, chronic diarrhea, lymphadenopathy, and abdominal pain. For suspicion of cerebral Whipple’s disease the patient should exhibit symptoms of neurological dysfunction, hemoparesis, cognitive dysfunction, dementia, seizures and ocular abnormalities. Ataxia, myelopathy and meningitis may also be present but are uncommon symptoms.

Accompanying Documentation:

Completed Special Bacteriology requisition form.

Comments:

Submit only specimens which are listed as samples ideal for the detection of a particular T. whipplei infection. If tissue blocks need to be returned to sender, please add courier information and account number to requisition. Alternatively, consider sending scrolls.

Methods and Interpretation of Results:

Results are based upon a real-time PCR assay of repeat sequences within the T. whipplei genome. Any positive or inconclusive results are repeated for confirmation by conventional PCR assays. A negative result does not eliminate the possibility of a T. whipplei infection but will only rule out a potential infection of the relative area of specimen origin. As with any laboratory test, the results of the test should be interpreted with consideration of all of the laboratory and clinical findings available.

Turnaround Time:

10 calendar days. Please note that during times when large numbers of samples are received or if tests must be repeated the turnaround time may be longer.

Contact:
Phone: (204) 789-2137
Fax: (204) 784-7509
References:
  1. Fenollar F, Birg ML, Gauduchon V, et al. 2003. Culture of Tropheryma whipplei from human samples: a 3-year experience (1999 to 2002). J. Clin. Micro. 41(8):3816-3822.
  2. Fenollar F , Laouira S , Lepidi H , Rolain JM , Raoult D . 2008. Value of Tropheryma whipplei quantitative polymerase chain reaction assay for the diagnosis of Whipple disease: usefulness of saliva and stool specimens for first-line screening. Clin. Infect. Dis. (47):659-67.
  3.  Lagier J-C, Lepidi H, Raoult D, et al. Systemic Tropheryma whipplei Clinical Presentation of 142 Patients with Infections (2010). Medicine 89:337-345.
  4. Panegyres PK. 2008. Diagnosis and management of Whipple’s disease of the brain. Prac. Neuro. (8):311-317.
  5. Rolain JM, Fenollar F, Raoult D. 2007. False positive PCR detection of Tropheryma whipplei in the saliva of healthy people. BMC Microbiology, 7:48.
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