Histoplasma DNA, PCR
- Test Information
- Specimen Requirements
- Shipping Information
Test Code
403
Clinical Significance
Histoplasma capsulatum (also known as Ajellomyces capsulatum) is a dimorphic fungus which is the causative agent of Histoplasmosis, which primarily affects the lungs. Most infections are asymptomatic, but the acute phase may present mild respiratory symptoms. Chronic histoplasmosis may progress to disseminated disease, which can be fatal, especially in immunocompromised individuals (e.g., HIV patients), though cases in healthy individuals have also been reported. Central nervous system (CNS) involvement may occur with or without disseminated disease and can present as meningitis or other neurologic manifestations; therefore, detection of Histoplasma DNA in cerebrospinal fluid (CSF) may support evaluation for CNS histoplasmosis when interpreted in conjunction with clinical findings and other laboratory results. Histoplasmosis is endemic to parts of the Americas, Asia, and Africa, but can occur elsewhere. The gold standard for diagnosis of 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 Histoplasma capsulatum directly from clinical specimens.
Methodology
Qualitative Real-Time PCR (Polymerase Chain Reaction)
Limitations
Specimens positive for Paracoccidioides brasiliensis, Aspergillus flavus, Aspergillus nidulans, and Aspergillus niger may cross react and test positive. When tested in cultures of 108 – 109 organisms/mL, cross-reactions occurred with Paracoccidioides brasiliensis, Aspergillus flavus, Aspergillus nidulans, and Aspergillus niger.
Fluconazole may interfere with assay sensitivity. When tested with Fluconazole at 7.0 ug/ mL in CSF specimens, interference occurred that lead to false negative test results.
Turnaround Time
Same Day***
Reference Range
Not detected
Interpretative Information
PCR testing should be done in conjunction with appropriate microbiology, antigen, and/or antibody testing. A positive PCR result indicates the DNA was detected in the sample and that organism could be the cause of disease. Some organisms (molds and yeasts) can be commensals (or colonizers) and found in non-sterile locations such as the respiratory, GI, and urinary systems – without causing disease. A negative result indicates DNA was not detected in the sample but does not rule-out that organism as the cause of disease. All results should be interpreted considering the full clinical picture.
Additional Information
This test was developed, and its analytical performance characteristics were determined by MiraVista Diagnostics. It has not been cleared or approved by the FDA; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.
Specimen Collection
BAL, Cavitary Effusion, tracheal aspirate*, or bronchial wash* in a sterile leak-proof container.
* Reported with a rare specimen comment applied.
Minimum Specimen Requirements
BAL, Cavitary Effusion, tracheal aspirate*, or bronchial wash* = 0.5 mL
* Reported with a rare specimen comment applied.
Specimen Stability
BAL
- Room Temperature/Ambient: 30 days
- Refrigerated: 30 days
- Frozen: 30 days
CSF
- Refrigerated: 5 days
- Frozen: 30 days
Transport Temperature
- Refrigerated
- Frozen
Shipping
Samples may be shipped on dry ice or frozen ice packs
* New positives may require confirmation.
** Turnaround times are provided as ranges, and may vary depending on daily testing volumes and specimen type.
*** Test set-up: Samples received by 10:30 AM are eligible for same-day testing. Same-day testing is not guaranteed and may vary based on daily test volume, sample receipt time, testing schedules, and sample type. Some samples may require pretreatment and/or confirmatory testing, which can extend turnaround time (TAT).
**** Patient's identification must be visible on the specimen container.
***** Specimens with particulate matter or viscosity that do not allow the specimen to be pipetted will be rejected.