Trichosporon Infections Workup

Updated: Feb 12, 2018
  • Author: Ryan C Maves, MD, FCCP, FCCM, FIDSA; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Workup

Laboratory Studies

The diagnosis of trichosporonosis is usually confirmed by a positive blood culture result obtained in the evaluation of a febrile (typically neutropenic) patient.

Important laboratory tests include blood culture sets, blood chemistries and hepatic transaminases, alkaline phosphatase, bilirubin, lactic acid dehydrogenase (LDH), and urinalysis with urine culture.

Urine cultures may be the first to grow Trichosporon in the setting of disseminated disease, [6] and it should not be presumed to be a contaminant or colonizer in the high-risk host (ie, in the setting of neutropenic fever). [1]

Trichosporon and C neoformans are closely related organisms and share a number of surface antigens. As such, the latex agglutination test results for serum cryptococcal antigen is often positive in the setting of disseminated trichosporonosis [7] (except trichosporonosis due to B capitatus [11] ). This widely used, rapid, and inexpensive test may provide an early clue about a Trichosporon infection. Because of changes in cell wall conformation, these test results may become negative during antifungal therapy, but newly negative test results do not imply a response to therapy. [1]

Investigational methods of rapid molecular diagnostics, such as DNA-based microarrays, [34] polymerase chain reaction (PCR), and pyrosequencing, [35] are in development but are not yet widely available for clinical use. [36, 37]

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Imaging Studies

Radiologic evaluation should include a chest radiograph and CT scans of the abdomen and pelvis. A CT scan of the chest is also frequently useful in the evaluation of the pulmonary infiltrate in the patient population at risk for Trichosporon infection, but confirmation of the diagnosis should rely on a tissue sample or on another useful clinical sample. Depending on the clinical picture, a CT scan or MRI of the brain may be indicated.

Endocarditis is rarely reported [16, 33] but is associated with high mortality rate (82% in a single series). Patients with prosthetic heart valves or persistently positive blood culture results should undergo echocardiography.

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Procedures

Bronchoscopy

When pulmonary infiltrates are present, bronchoscopy is a useful means of obtaining samples if the patient can tolerate the procedure. Positive culture results from a bronchial lavage support the diagnosis. [26]

Biopsy

Open-lung biopsy may be required for definitive diagnosis because of the large number of viral, bacterial, protozoal, and fungal pathogens that can cause disease in patients with pulmonary infiltrates.

Lesions of the GI tract may be accessible for biopsy and may yield a diagnosis before blood cultures return positive findings.

Skin lesions occur in roughly 10% of patients with disseminated trichosporonosis. Biopsy of suspicious lesions in immunocompromised patients with fever may facilitate early diagnosis.

Liver lesions or other visceral lesions may also require biopsy for diagnosis and optimal management.

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Histologic Findings

Grossly, infected tissues may contain micronodules (0.5-1.0 cm), occasionally surrounded by red rims. The GI tract may demonstrate ulceration and erosion associated with hemorrhage and hemorrhagic infarction. [7]

Microscopic examination of a nodule may reveal a necrotic center with fungal elements either in a starburst pattern or more loosely organized. Fungal elements may be observed invading the vasculature. Visualization of blastoconidia, arthroconidia, hyphae, and pseudohyphae in a histologic section supports the diagnosis of invasive Trichosporon infection. [7, 13] The cellular inflammation surrounding the fungal elements may vary, occasionally associated with hemorrhage. Granulomatous inflammation with multinucleated giant cells has been reported. [38]

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