Histoplasma and Blastomyces are among the most prevalent fungal pathogens in the United States and can cause serious pulmonary illness. In this test-specific episode of the "Answers From the Lab" podcast, Elitza Theel, Ph.D., describes Mayo Clinic Laboratories' innovative Histoplasma and Blastomyces assay — a cost-effective alternative to existing tests.

"Our assay will detect antigen from both Histoplasma and Blastomyces in serum using a single test," Dr. Theel says.

Clinicians generally order two separate tests because it's nearly impossible to clinically distinguish which pathogen is causing a patient's symptoms. But cross-reactivity of antigens is common in the two assays — meaning that a patient infected with one of the pathogens is likely to test positive on both assays.

The Histoplasma and Blastomyces test yields the same information: whether the patient's serum is positive or negative for one of the pathogens. "But patients can now pay for a single test rather than two," Dr. Theel says. "The change in testing process wouldn't negatively impact care because these pathogens are treated quite similarly with antifungals."

If needed, Mayo Clinic Laboratories offers additional testing that can differentiate the two pathogens.

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Testing

HIBAG | Histoplasma/Blastomyces Antigen, Enzyme Immunoassay, Serum

Useful information

• Diagnosing Histoplasma capsulatum or Blastomyces dermatitidis infection without differentiation between the organisms.
• Monitor antigen levels following initiation of antifungal treatment.

Specimen requirements

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.

Performance information

Analytic time: Same day/1 day

Days performed: Monday through Saturday

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