Diagnosis of Pulmonary Infections Due to Endemic Fungi

Abstract

Endemic mycoses including Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, and Talaromyces are dimorphic fungi that can cause a variety of clinical manifestations, including respiratory infections. Their pulmonary presentations are variable, and diagnosis is often delayed as they can mimic other infectious and non-infectious causes of pulmonary disease. Delay in diagnosis can lead to unnecessary antibiotic use, repeat hospitalizations, and increased morbidity and mortality. The diagnosis of endemic fungal pulmonary infections often relies on multiple diagnostic tests including culture, tissue histopathology, antigen assays, and antibody assays. Due to the increased use of immunosuppressive agents and the widening geographic ranges where these infections are being found, the prevalence of endemic fungal infections is increasing. Physicians need to be aware of the clinical manifestations of pulmonary infections due to endemic fungal in order to ensure that the proper diagnostic work up is obtained promptly. A high index of suspicion is particularly important in patients with suspected pulmonary infections who have failed to improve despite antibiotics in the appropriate setting. We present a review diagnostic testing for pulmonary infections due to endemic mycoses.

Noninvasive Testing and Surrogate Markers in Invasive Fungal Diseases

“… Adapted from Poplin et al [ 159 ]. Abbreviations: Ab, antibody; APH, acute pulmonary histoplasmosis, CPH, subacute pulmonary histoplasmosis; DID, double immunodiffusion; EIA, enzyme immunoassay; ELISA, enzyme-linked immunosorbent assay; IDCF, immunodiffusion complement fixation; IDTP, immunodiffusion tube precipitin; SPH, subacute pulmonary histoplasmosis.…”

Disseminated Histoplasmosis with Underlying Sarcoidosis-Rheumatoid Arthritis Overlap Syndrome: An Example of Diagnostic Test Threshold of Detection Affecting Test Results and Patient Care

“…This is a predictable scenario. Although culture is often considered a gold standard for histoplasmosis, results take 2–8 weeks, frequently too long to aid in diagnosis [ 11 ].…”

Blastomycosis—Some Progress but Still Much to Learn

“…Fungal culture is another traditional method of diagnosis. While often more sensitive, culture may take up to five weeks to grow Blastomyces (though one or two weeks is more common) [ 87 ]. One interesting study found cultures from different respiratory fluids to have different yields, although they were limited to some degree by small numbers.…”

“…Blastomyces yeast is typically described as broad-based budding, and it is 8–20 µM in diameter with a doubly refractile cell wall [ 87 ]. Interestingly, giant forms have been described occasionally that may be confused with Coccidioides [ 88 ].…”

“…Generally, respiratory cultures seem to have sensitivities >70%, with exact numbers depending on the fluid type. Culturing multiple specimen types (tracheal secretions, sputum, and bronchoalveolar lavage (BAL) fluid) seems to be additive [ 87 , 91 ]. A DNA probe (AccuProbe, Hologic, Inc., San Diego, CA, USA) is also available to be used on cultures growing fungi that have not yet been identified; however, this may cross-react with Emergomyces spp.…”