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Extrapulmonary and Other Pneumocystis jirovecii Infections Diagnosed via Fungal Cell-Free DNA Using Giant
Jo-Anne H Young1, Karam M Obeid1, Minggan Li2
1Department of Medicine, Division of Infectious Disease and International Medicine, University of Minnesota, MMC 250, 420 Delaware St. SE, Minneapolis, MN 55455, USA.
Abstract:
Clinical suspicion and diagnosis of Pneumocystis infections rely on a combination of compatible clinical, radiologic, and diagnostic findings. We noted an extrapulmonary Pneumocystis infection when evaluating residual plasma samples from patients with possible invasive fungal infections using cell-free DNA (cfDNA) Giant Magnetoresistance (GMR) (FungiFlex®, Zepto Life Technology). A man, immunocompromised for 27 years due to kidney transplantations, developed fever and rising aminotransferase enzyme levels during transient escalation of immunosuppressive therapy. Except for an elevated (1,3)-beta-D-glucan, further laboratory testing did not find the highly suspected histoplasmosis. Daily plasma blood samples for cfDNA fungal GMR testing were examined for histoplasmosis; however, the fungal GMR signal was only positive for Pneumocystis jirovecii in all four samples. In retrospect, the transient escalation of immunosuppressive dosing created a temporary net state of over-immunosuppression that was permissive for Pneumocystis. Additionally, the assay corroborated pulmonary pneumocystosis for a second patient, was negative for a third patient with colonization, and was negative for a fourth patient when fevers correlated with an abdominal bacterial process. Within the exploratory nature of the findings, we find that the reference standard for defining Pneumocystis is imperfect and may not accurately identify all cases. cfDNA testing may supplement existing laboratory testing and improve the diagnosis of Pneumocystis.
Insights
Cell-free DNA (cfDNA) testing detected Pneumocystis jirovecii in an immunocompromised patient, suggesting it can aid in diagnosing Pneumocystis infections when traditional methods fall short.
Area of Science:
- Medical Diagnostics
- Infectious Diseases
- Mycology
Background:
- Pneumocystis infections diagnosis relies on clinical, radiologic, and laboratory findings.
- Extrapulmonary Pneumocystis infections are challenging to diagnose.
- Current diagnostic standards for Pneumocystis may be imperfect.
Purpose of the Study:
- To evaluate the utility of cell-free DNA (cfDNA) Giant Magnetoresistance (GMR) testing for diagnosing Pneumocystis infections.
- To investigate the potential of cfDNA testing in cases where traditional diagnostics are inconclusive.
Main Methods:
- Utilized cfDNA GMR (FungiFlex®) on plasma samples from patients with suspected invasive fungal infections.
- Analyzed samples from four patients, including one with extrapulmonary Pneumocystis and others with suspected or confirmed infections/colonization.
- Correlated cfDNA GMR results with clinical presentation and other laboratory markers like (1,3)-beta-D-glucan.
Main Results:
- cfDNA GMR detected Pneumocystis jirovecii in a patient with extrapulmonary infection and fever, despite negative initial workup for histoplasmosis.
- The assay corroborated pulmonary pneumocystosis in a second patient.
- The assay was negative in a patient with colonization and another with a bacterial process.
Conclusions:
- cfDNA testing shows promise as a supplementary tool for diagnosing Pneumocystis infections, including extrapulmonary cases.
- The findings suggest cfDNA GMR may improve diagnostic accuracy for Pneumocystis, potentially overcoming limitations of current reference standards.
- Transient immunosuppression escalation was identified as a factor potentially permitting Pneumocystis reactivation.
