Toxoplasma DNA detection by PCR

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General Information

Lab Name
Toxoplasma DNA detection by PCR
Lab Code
TOXDNA
Epic Name
Toxoplasma DNA detection by PCR
Description

Detection of Toxoplasma gondii DNA

The protozoan Toxoplasma gondii is estimated to be carried by one third of the world's population with infection typically occurring by eating infected meat, contact with a cat that has itself recently been infected, or by transmission from mother to fetus. During acute toxoplasmosis, symptoms are often influenza-like: swollen lymph nodes, or muscle aches and pains that last for a month or more. Rarely, a patient with a fully functioning immune system may develop eye damage from toxoplasmosis.

Toxoplasmosis can be difficult to distinguish from that of primary central nervous system lymphoma, and as a result, the diagnosis is made by a trial of therapy (pyrimethamine, sulfadiazine + leucovorin), or a brain biopsy if the drugs produce no effect. Serologic testing for both IgG and IgM can determine if and when individual is/was infected. Additionally, PCR has been successfully used to diagnose congenital, ocular, cerebral and disseminated toxoplasmosis. PCR performed on amniotic fluid has revolutionized the diagnosis of fetal T. gondii infection by enabling an early diagnosis to be made, thereby avoiding the use of more invasive procedures on the fetus. PCR has allowed detection of T. gondii DNA in brain tissue, CSF, vitreous and aqueous fluid, BAL, urine and amniotic fluid.

Among PCR assays, the B1 gene is consistently determined to be a useful target. B1 is a tandem-arrayed 35-fold-repetitive gene which has been used for both detection and typing of Toxoplasma strains in clinical samples. The UWMC Molecular Diagnosis laboratory utilizes a 2-step, hemi-nested PCR approach to amplify a region of the B1 gene. Identification of Toxoplasma gondii depends on Real-Time PCR melting curve and evaluation of the sequenced product.

Forms & Requisitions

Molecular Microbiology Order Form

Synonyms
molecular Toxoplasma, molecular Toxoplasma gondii, Parasite identification, Parasite PCR, Synonyms: Toxoplasma PCR, Toxoplasma detection, Toxoplasma gondii detection, Toxoplasma gondii identification, Toxoplasma gondii PCR, Toxoplasma gondii sequencing, Toxoplasma identification, Toxoplasma sequencing, Toxoplasmosis, universal PCR
Components
Code Name
TOXRS Toxoplasma PCR: Detection, B1
TOXID Toxoplasma PCR: Identification, B1
TOXSI Toxoplasma PCR: Specimen Description
TOXSPI Toxoplasma PCR: External Identifier
TOXSR Toxoplasma PCR: Special Requests
TOXSC Toxoplasma PCR: Specimen Comments
TOXNAE Toxoplasma PCR: Specimen DNA Extraction
TOXREV Toxoplasma PCR: Pathologist Review
TOXME Toxoplasma PCR: Method Note

Interpretation

Guidelines
Method

DNA extraction, nucleic acid purification, polymerase chain reaction (PCR), sequencing

Reference Range
See individual components

Ordering & Collection

Specimen Type
Tissue (Fresh frozen or paraffin-embedded), Fluid (see Acceptable Specimens for details)
Collection

Acceptable specimens are listed below. Please see Molecular Microbiology Specimen Submission for complete specimen collection and handling instructions.

Shipping/Handling

  • Fresh frozen tissue/fluid specimens should be collected into a DNA free container labeled with at least two identifiers and be submitted and maintained on dry ice.
  • Formalin Fixed Paraffin-embedded tissues (FFPE, PET) can be sent ambient or with ice packs during warmer summer months to prevent melting.

Acceptable Specimens

*Mycobacterium avium complex DNA Detection [MAVDNA] can be ordered on sputum

**Fungal PCR reflex NGS [FUNDNA] and Fungal DNA Detection by PCR (without reflex to NGS) [NRFDNA] may have interference due to some lots of eSwabs which have been found to contain Saccharomyces cerevisiae DNA, resulting in false positive detection. Clinical correlation and/or retesting with a different collection method is advised. The detection of S. cerevisiae from eSwab specimens can interfere with our ability to rule out other fungal DNA.

    Unacceptable Specimens

    • Blood, serum, plasma, stool/rectal swabs
    • No citrated or heparinized solutions
    • Tissues floating in formalin
    • Swab/fluid collected in tube containing agar

    Optimal Quantity:

    • Fresh Tissue: 0.3-1.0 cm^3
    • Fluid: 0.2-1 mL
    • Formalin Fixed Paraffin-embedded Tissue (FFPE/PET): blocks are preferred over scrolls/unstained slides and will be sent back to client upon completion of testing
    • Scrolls/unstained slides: cross-sectional area >1cm^2 send 10 sections of 10µm thickness, if <1cm^2 send 20 sections if available

    Please note: We do not need a separate specimen aliquot for each test ordered. Only a single specimen aliquot or block of optimal quantity is necessary for performing multiple tests. If multiple aliquots or blocks of optimal quantity are sent, up to 2 will be pooled.

    Fresh tissue is the optimal specimen of choice, as it reduces the chance of introducing exogenous DNA templates or microorganisms during embedding/fixation. Formalin fixation dramatically reduces the sensitivity of the assays due to reduced template yield and quality.

    Forms & Requisitions

    Molecular Microbiology Order Form

    Handling Instructions

    Please see Molecular Microbiology Specimen Submission for complete specimen collection and handling instructions.

    Quantity
    Requested: See "Collection" for Optimal Quantity
    Minimum: Specimens below optimal quantity are acceptable for testing, however, diagnostic yield is generally proportional to specimen size.

    Processing

    Receiving Instructions

    UWMC/HMC: Store and send fresh tissue/fluid specimens refrigerated, if specimen storage and transport will exceed 8 hours, freeze at -20°C. Freeze all fresh tissue/fluid specimens at -20°C upon arrival in UW Molecular Microbiology.

    Misc Sendout

    Performance

    Lab Department
    Micro Molecular Diag(MMD)
    Frequency
    Fresh frozen tissues/fluids result in 2-3 business days after receipt of specimen. Formalin Fixed Paraffin-embedded tissues result in 3-4 business days after receipt of specimen.
    Available STAT?
    No
    Performing Location(s)
    UW-MT Microbiology, Molecular Diagnostics
    206-520-4600

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    Shipping Address

    Attn: Molecular Microbiology
    UW CLSPS
    1601 Lind Ave SW Room 117
    Renton, WA 98057
    Phone: 206-520-4600
    Alternate phone: 206-598-6147

    Performing Lab Address

    Clinical Microbiology Lab, NW177
    University of Washington Medical Center
    1959 NE Pacific Street
    Seattle, WA 98195
    Phone: 206-598-5735
    Alternate phone: 206-598-6147

    Contact Information

    Please e-mail us with any questions or comments you may have. Your inquiry will be answered as soon as possible.

    email: molmicdx@uw.edu

    The Molecular Microbiology lab is open from Monday-Friday, 7am-4pm PDT.

    Billing inquiries and requests for faxed reports can be made to our Client Services Department at (206) 520-4600 or (800) 713-5198.

    For results or other inquiries, we can be reached by phone at the following numbers:

    • Phone: (206) 598-5735
    • Alternate phone: (206) 598-6147
    • FAX: (206) 520-4903

    For assistance during weekends, holidays and after hours, please contact Lab Medicine Resident at (206) 598-6190

    Billing & Coding

    CPT Codes
    87798
    LOINC
    29904-0
    Interfaced Order Code
    UOW4464