Test Catalog

Test Id : HBRP

Histoplasma capsulatum/Blastomyces species, Molecular Detection, PCR, Varies

Useful For
Suggests clinical disorders or settings where the test may be helpful

Rapid detection of Histoplasma capsulatum and Blastomyces dermatitidis DNA

 

An aid in the rapid diagnosis of histoplasmosis and blastomycosis

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (PCR)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Histoplasma/Blastomyces PCR

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Specimen Type
Describes the specimen type validated for testing

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. Therefore, the UHIST / Histoplasma Antigen, Urine is the recommended test for this specimen source.

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.

 

NALC/NaOH-digested specimen must arrive within 7 days of digestion.

Necessary Information

Specimen source is required.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

The high sensitivity of amplification by PCR 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, CSF, bone marrow

Container/Tube: Sterile container

Specimen Volume: 1 mL

 

Specimen Type: Respiratory

Sources: BAL, 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: 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.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

Body Fluid or Respiratory Specimen: 0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Other 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 Specimen >7 days old

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred) 7 days
Ambient 7 days
Frozen 7 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Rapid detection of Histoplasma capsulatum and Blastomyces dermatitidis DNA

 

An aid in the rapid diagnosis of histoplasmosis and blastomycosis

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Meningitis/Encephalitis Panel Algorithm in Special Instructions.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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. Patients at risk for disseminated disease include neonates and immunosuppressed individuals, particularly those with AIDS, hematologic malignancies, or a recent transplant. Primary infections are acquired through inhalation of microconidia that are present in the environment. In the United States, most cases of blastomycosis and histoplasmosis occur along the Ohio and Mississippi River valleys.

 

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. The organisms can be identified after growth in culture using traditional macro- and microscopic morphologic techniques or through the use of nucleic acid hybridization probes. Hybridization probe-based procedures are rapid and demonstrate good sensitivity and specificity from culture, although some cross-reactivity with relatively uncommon fungal organisms has been reported. Additional diagnostic tests that can be utilized for these organisms include stains, histopathology, serology, and antigen detection with each of these methods offering advantages and limitations depending on the stage of the illness and the status of the patient. Fungal stains (eg, calcofluor white) offer a rapid diagnostic approach, but demonstrate poor sensitivity and specificity. Serologic tests such as complement fixation and immunodiffusion are noninvasive, but are laborious, subjective, and may show low sensitivity, especially in immunocompromised hosts. Antigen detection also offers a noninvasive approach, but has been demonstrated to show cross-reactivity with antigens from closely related fungal species.

 

Molecular techniques have been established as sensitive and specific methods for the diagnosis of infectious diseases and have the added advantage of a rapid turnaround time for results. Due to the limitations of conventional diagnostic methods for blastomycosis and histoplasmosis, a single tube, real-time PCR assay was developed and verified for the detection and differentiation of B dermatitidis/gilchristii and H capsulatum directly from clinical specimens.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Not applicable

Interpretation
Provides information to assist in interpretation of the test results

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 PCR assay and should always be performed when the PCR is negative.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This rapid 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 (BAL) fluid is low and a negative result does not rule out infection.

Supportive Data

Analytical Sensitivity and Specificity:

The analytical sensitivity of the assay was determined to be less than or equal to 100 copies/microliter for both Blastomyces dermatitidis/gilchristii and Histoplasma capsulatum. The B dermatitidis/gilchristii melt peak is read at 670 nm and has a melting temperature (Tm) of 66 degrees C + or - 0.26 degrees C (mean + or - standard deviation), while the H capsulatum read at 610 nm has a Tm of 61 degrees C + or - 0.27 degrees C. A National Center for Biotechnology Information (NCBI) Basic Local Alignment Search Tool (BLAST) search of the primer, probe, and target sequences for both B dermatitidis/gilchristii and H capsulatum did not yield any potentially cross-reacting sequences. In addition, testing of nucleic acids from 179 potentially cross-reacting microbes commonly encountered in the clinical laboratory including bacteria, fungi, parasites, and viruses demonstrated no cross-reactivity with other organisms. The list of organisms is available upon request.

 

Sensitivity and Specificity from Cultured Isolates:

The sensitivity of the assay from isolates grown in culture was 100% (61/61) and 94.5% (51/54) for B dermatitidis/gilchristii and H capsulatum, respectively. The specificity of the assay was 100% for both organisms as no cross-reactivity was detected in the other non-B dermatitidis/gilchristii or non-H capsulatum cultures evaluated.

 

Clinical Sensitivity and Specificity Directly from Specimens:

A total of 797 clinical specimens were tested concurrently by fungal culture and the real-time PCR assay to assess clinical sensitivity and specificity. The sensitivity and specificity of the PCR assay for B dermatitidis/gilchristii was 86% (12/14 positive) and 99.4% (778/783 negative), respectively. The overall sensitivity and specificity of the PCR assay for H capsulatum was 73.3% (11/15 positive) and 100% (782/782 negative), respectively. Of note, the recovery of H capsulatum from bronchoalveolar lavage (BAL) fluid was low (2 PCR positives of 6 culture positives), which accounted for all of the falsely negative specimens. Therefore, a negative result from BAL fluid does not rule out H capsulatum infection due to low sensitivity from this specimen source.

 

Due to the low number of positive specimens obtained clinically despite testing almost 800 specimens over a period of 1 year, spiking studies using a plasmid control for both organisms were also performed using negative specimens representing various specimen types (30 each of pleural fluid, sputum, BAL fluid, cerebrospinal fluid, tissue, bone, sterile body fluids, urine, and blood). The spiking studies demonstrated a sensitivity of the PCR assay of 100% (30/30 positive) for B dermatitidis/gilchristii across all specimen types except blood (97% sensitive; 29/30 positive). The PCR assay had 100% (30/30) sensitivity for H capsulatum across all spiked specimen types except sputum and blood which had 98% and 97% sensitivity respectively.

 

Inhibition studies:

The overall extraction and amplification inhibition rate of the assay using both targets was less than 1% (2/330 inhibited). Extraction inhibition occurred in 1 of 30 blood specimens for B dermatitidis/gilchristii and H capsulatum, and 1 of 60 sputum specimens for H capsulatum.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Kauffman CA: Histoplasmosis. Clin Chest Med 2009;30:217-225

2. Wheat LJ, Freifeld AG, Kleiman MB, et al: Clinical practice guidelines for the management of patients with histoplasmosis: 2007 update by the Infectious Diseases Society of America. Clin Infect Dis 2007;45:807-825

3. Chapman SW, Bradsher RW Jr, Campbell GD Jr, et al: Practice guidelines for the management of patients with blastomycosis. Infectious Diseases Society of America. Clin Infect Dis 2000;30:679-683

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Following specimen processing, nucleic acids are extracted using the MagNA Pure Compact (Roche Applied Sciences). The extract is then transferred to a cuvette for amplification using the LightCycler real-time PCR platform (Roche Applied Sciences). The LightCycler is an automated instrument that amplifies and monitors the development of target nucleic acid (amplicon) after each cycle of PCR. The detection of amplicon is based of fluorescence resonance energy transfer (FRET), which utilizes hybridization probes. The presence of the specific organism nucleic acid is confirmed by performing a melting curve analysis of the amplicon. Primers and 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, et al: 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)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87798 x 2

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports