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HelpTest Code HBRP Histoplasma capsulatum/Blastomyces species, Molecular Detection, PCR, Varies
Reporting Name
Histoplasma/Blastomyces PCRUseful For
Rapid detection of Histoplasma capsulatum and Blastomyces dermatitidis DNA
Aiding in the rapid diagnosis of histoplasmosis and blastomycosis
Testing Algorithm
For more information see Meningitis/Encephalitis Panel Algorithm
Method Name
Real-Time Polymerase Chain Reaction (PCR)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesOrdering Guidance
Urine is not an acceptable source for this assay. Studies indicate that Histoplasma DNA is not routinely found in the urine of patients with disseminated histoplasmosis. The recommended test for urine specimens is HSTQU / Histoplasma Antigen, Quantitative Enzyme Immunoassay, Random, Urine.
Additional Testing Requirements
This test should always be performed in conjunction with fungal culture; order FGEN / Fungal Culture, Routine.
Shipping Instructions
Specimen must arrive within 7 days of collection; specimens received after 7 days will be rejected.
N-acetyl-l-cysteine-sodium hydroxide (NALC/NaOH)-digested specimen must arrive within 7 days of digestion.
Necessary Information
Specimen source is required.
Specimen Required
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 Histoplasma or Blastomyces species DNA is not likely.
Submit only 1 of the following specimens:
Specimen Type: Body fluid
Sources: Body, spinal fluid, bone marrow
Container/Tube: Sterile container
Specimen Volume: 1 mL
Specimen Type: Respiratory
Sources:Â Bronchoalveolar lavage, bronchial washing, sputum
Container/Tube: Sterile container
Specimen Volume: 1 mL
Specimen Type: Tissue or bone
Container/Tube: Sterile container
Specimen Volume: 5-10 mm
Collection Instructions: Collect a fresh tissue or bone specimen.
Acceptable:
Specimen Type: N-acetyl-l-cysteine-sodium hydroxide (NALC/NaOH)-digested respiratory specimens
Sources: Lavage fluid, bronchial washing, gastric washing, respiratory fluid, sputum, or tracheal secretion
Container/Tube: Sterile container
Specimen Volume: 2 mL
Collection Instructions:
1. Submit digested specimen treated with NALC/NaOH.
2. Clearly indicate on container and order form that specimen is a digested specimen.
Specimen Minimum Volume
Body fluid or respiratory specimen: 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Refrigerated (preferred) | 7 days | |
| Ambient | 7 days | ||
| Frozen | 7 days |
Reject Due To
| Â Specimen in anaerobe vial or viral transport medium (including but not limited to M4, M5, BD viral transport media, thioglycolate broth) Feces Swab Tissue in formalin fluid Urine |
Reject |
Special Instructions
Reference Values
Not applicable
Day(s) Performed
Monday through Sunday
CPT Code Information
87798 x 2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| HBRP | Histoplasma/Blastomyces PCR | 81653-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| SRC78 | Histo/Blasto Source | 31208-2 |
| 32457 | Histo/Blasto Result | 81653-8 |
Clinical Information
Infections with Blastomyces dermatitidis and Histoplasma capsulatum cause a variety of clinical manifestations ranging from self-limited, mild pulmonary illness to potentially life-threatening, disseminated disease. Primary infections are acquired through inhalation of conidia that are present in the environment. In the United States, most cases of blastomycosis and histoplasmosis occur along the Ohio and Mississippi River valleys, although recent studies suggest the geographic area of endemicity may be expanding.
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The gold standard for diagnosis of blastomycosis and histoplasmosis remains isolation of the organisms in culture. Although sensitive, recovery in culture and subsequent identification may require days to weeks. This polymerase chain reaction assay can provide rapid and specific detection and differentiation of B dermatitidis/gilchristii and H capsulatum directly from clinical specimens.
Interpretation
A positive result for Histoplasma capsulatum indicates presence of Histoplasma DNA; a positive result for Blastomyces dermatitidis/gilchristii indicates presence of Blastomyces DNA.
A negative result indicates absence of detectable H capsulatum and B dermatitidis/gilchristii DNA. Fungal culture has increased sensitivity over this polymerase chain reaction (PCR) assay and should always be performed when the PCR is negative.
Cautions
This rapid polymerase chain reaction (PCR) assay detects Histoplasma capsulatum and Blastomyces dermatitidis nucleic acid and, therefore, does not distinguish between the presence of viable, disease-related organisms and nucleic acid persisting from previous, treated disease. Test results should be correlated with patient symptoms and clinical presentation before a definitive diagnosis is made.
A negative result does not rule out the presence of H capsulatum or B dermatitidis/gilchristii because the organism may be present at levels below the limit of detection for this assay.
The sensitivity of the PCR assay from bronchoalveolar lavage fluid is low, and a negative result does not rule out infection.
Method Description
Following specimen processing, nucleic acids are extracted using the MagNA Pure instrument (Roche Applied Sciences). The extract is then amplified using the LightCycler real-time polymerase chain reaction (PCR) platform (Roche Applied Sciences). The presence of the specific organism nucleic acid is confirmed by performing a melting curve analysis of the amplicon. Primers and fluorescence resonance energy transfer (FRET) hybridization probes were designed to target a 174-base pair (bp) region of the histidine kinase (DRK-1) gene of Blastomyces dermatitidis/gilchristii and a 192-bp region of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene of Histoplasma capsulatum, respectively. The acceptor probe for B dermatitidis/gilchristii was labeled with a Red-705 dye, while the acceptor probe for H capsulatum was labeled with a Red-640 dye. Labeling the acceptor probes with 2 different dyes allows for simultaneous detection and differentiation of B dermatitidis/gilchristii and H capsulatum within a single PCR assay.(Babady NE, Buckwalter SP, Hall L, Le Febre KM, Binnicker MJ, Wengenack NL: Detection of Blastomyces dermatitidis and Histoplasma capsulatum from culture isolates and clinical specimens by use of real-time PCR. J Clin Microbiol. 2011;49:3204-3208)