Toxoplasma DNA detection by PCR

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General Information

Lab Name
Toxoplasma DNA detection by PCR
Lab Code
TOXDNA
Epic Ordering
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, amniotic fluid and peripheral blood.

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 SYBR-green melting curve and evaluation of the sequenced product.

For more information on this test, to download a requisition form, and for a list of acceptable and unacceptable specimens, please refer to: Molecular Diagnosis Microbiology Section Website

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

Interpretation

Method

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

Reference Range
See individual components
Guidelines

Ordering & Collection

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

Acceptable specimens are listed below. Please see this page for complete specimen collection and handling instructions.

Specimens should be collected into a DNA free container labeled with at least two identifiers.

Acceptable Specimens

  • Fresh frozen tissue
  • Fresh frozen fluid: any body fluid is acceptable if it is not listed under Unacceptable Specimens. See common examples below.
  • Formalin Fixed Paraffin-embedded tissues (FFPE, PET): blocks, scrolls, and unstained slides are acceptable
  • eSwabs and UTM (universal transport media)

Common acceptable body fluid examples: cerebrospinal fluid, pleural fluid, pericardial fluid, urine, bronchial lavage, joint fluid, bone marrow, vitreous fluid, etc.

Additional Acceptable Specimens

  • Sputum

Unacceptable Specimens

  • Blood, serum, plasma, stool
  • No citrated or heparinized solutions
  • No SPS (Sodium Polyanethole Sulfonate) e.g. Wampole Isolator Tubes
  • Tissues floating in formalin
  • Swab/fluid collected in tube containing agar
Handling Instructions

Fresh frozen tissue/fluid specimens should 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.


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 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.

Quantity
requested: See Optimal Quantity above
minimum: Specimens below optimal quantity are acceptable for testing, however, diagnostic yield is generally proportional to specimen size.

Processing

Processing

UWMC/HMC – store and send specimen refrigerated and freeze specimens at -20°C upon arrival in UW-ML Microbiology. If specimen storage and transport will exceed 8 hours, freeze at -20°C.

Freeze specimens at -20°C upon arrival

Outside Laboratories: Freeze specimens in sterile containers at -20°C. Transport all specimens on dry ice.

Performance

LIS Dept Code
Micro Molecular Diag (MMD)
Performing Location(s)
UW-MT Microbiology, Molecular Diagnostics
206-520-4600

Clinical Lab, Room # NW177,
University of Washington Medical Center,
1959 NE Pacific street, Seattle, WA 98195
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

Billing & Coding

CPT codes
87798
LOINC
29904-0
Interfaced Order Code
UOW4464