Karius Medical Case Report: Detection of Blastomyces dermatitidis | Karius
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Karius Medical Case Report: Detection of Blastomyces dermatitidis

We report the following clinical scenario:

An elderly male from the St. Lawrence River Valley had a renal transplant and was on immunosuppressive treatment. He was admitted to hospital with sepsis and bilateral pneumonia, and was intubated for respiratory failure. 

A bronchoscopy was performed and fungal stains of respiratory samples showed broad-budding yeast.  A Karius Test was also sent.

Karius Test result: Blastomyces dermatitidis

This result is an example of a group of dimorphic fungi that can exist in either mold or yeast form. A familiar adage to learn the difference is: “Mold in the Cold (environment), Yeast in the Beast (human).”

Dimorphic fungal infections are rare, and are classically associated with specific geographic areas or activities.

One example is coccidioidomycosis, or “Valley Fever,” caused by a number of Coccidioides species (including C. immitis and C. posadasii). It tends to grow in the soil in arid areas of California, Texas, Arizona, and New Mexico. The spores can survive for years despite heat and harsh conditions. It is spread via inhalation when the spores in the soil are disrupted and become airborne. It begins as a pulmonary infection and can become disseminated to involve skin, bones, joints, and the central nervous system. An estimated 100,000 infections per year occur in the United States.

A second example is histoplasmosis, also known as “Cave Disease,” and “Mississippi Valley Disease.” It is caused by Histoplasma capsulatum, and its spores are typically associated with bat guano or bird droppings. Cave spelunking and chicken breeding are risk factors, and the geographic range is in the Mississippi and Ohio River Valleys as well as international. Histoplasmosis infection occurs via spore inhalation and leads to mild pulmonary disease, chronic pneumonia, or disseminated disease.

A final example, affecting the patient in this clinical scenario, is blastomycosis. This infectious disease is caused by the fungus Blastomyces dermatitidis, and is associated with regions including the Great Lakes Basin, St. Lawrence River Valley, central Appalachian mountains, and Mississippi River Valley. Blastomycosis can have numerous presentations, including flu-like illness, pneumonia, tuberculosis-like illness, central nervous system disease, and skin lesions.

In this case, Blastomycosis was already suspected for the patient based on the morphology of yeast grown from respiratory samples. 

The Karius result confirmed the morphological diagnosis while identification of the species from other diagnostic methods was still pending.

The physician was able to confirm their suspicion and confidently continue with directed antifungal therapy.

This is part of a series of Karius Medical Case Reports. In this case, the Karius Test was able to accurately identify infection with B. dermatitidis in a clinically relevant timeframe, allowing targeted treatment for the patient. We will discuss additional case reports in future posts.

 

References

https://www.cdc.gov/fungal/diseases/blastomycosis/index.html
https://www.cdc.gov/fungal/diseases/coccidioidomycosis/index.html
https://www.cdc.gov/fungal/diseases/histoplasmosis/index.html
 

DISCLAIMER: Case descriptions have been modified to protect patient privacy and, while every attempt has been made to provide accurate information, errors may occur. This information is provided for educational purposes only, and is not intended to be used as medical advice.