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Mayo Test ID HBRP Histoplasma capsulatum/Blastomyces species, Molecular Detection, PCR, Varies


Ordering 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:  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.


Useful For

Rapid detection of Histoplasma capsulatum and Blastomyces dermatitidis DNA

 

Aiding in the rapid diagnosis of histoplasmosis and blastomycosis

Method Name

Real-Time Polymerase Chain Reaction (PCR)

Reporting Name

Histoplasma/Blastomyces PCR

Specimen Type

Varies

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

 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

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.

 

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.

Reference Values

Not applicable

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.

Clinical Reference

1.Wheat LJ, Azar MM, Bahr NC, Spec A, Relich RF, Hage C: Histoplasmosis. Infect Dis Clin North Am. 2016 Mar;30(1):207-227. doi: 10.1016/j.idc.2015.10.009

2.Azar MM, Loyd JL, Relich RF, Wheat LJ, Hage CA: Current concepts in the epidemiology, diagnosis, and management of Histoplasmosis syndromes. Semin Respir Crit Care Med. 2020 Feb;41(1):13-30. doi: 10.1055/s-0039-1698429

3.Linder KA, Kauffman CA, Miceli MH: Blastomycosis: A review of mycological and clinical aspects. J Fungi (Basel). 2023 Jan 14;9(1):117. doi: 10.3390/jof9010117

4.Smith DJ, Williams SL; Endemic Mycoses State Partners Group; Benedict KM, Jackson BR, Toda M: Surveillance for Coccidioidomycosis, Histoplasmosis, and Blastomycosis - United States, 2019. MMWR Surveill Summ. 2022 Aug 19;71(7):1-14. doi: 10.15585/mmwr.ss7107a1

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)

Day(s) Performed

Monday through Sunday

Report Available

1 to 3 days

Specimen Retention Time

7 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

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

Testing Algorithm

For more information see Meningitis/Encephalitis Panel Algorithm