Other opportunistic yeasts (Trichosporon, Rhodotorula, Saccharomyces)
- Fungus
- For completeness
Uncommon yeasts that cause bloodstream infections in patients with cancer, catheters or probiotics. Some resist the usual antifungals.
Also called: rare yeasts, Trichosporon asahii, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, Saccharomyces boulardii
Quick facts
- Type
- Fungus · Yeasts and yeast-like fungi
- Gram / shape
- Trichosporon
- Spread
- Endogenous · Central venous catheters
- Causes
- Trichosporon fungemia
- Treatment
- Trichosporon
At a glance
- Shape
- Trichosporon: blastoconidia, hyphae and rectangular arthroconidia; Rhodotorula and Saccharomyces: oval budding yeasts
- Family
- Trichosporon and Rhodotorula: Basidiomycota; Saccharomyces: Ascomycota
- Type
- Yeasts and yeast-like fungi
- Stain
- Gram or calcofluor; blood culture and identification by mass spectrometry or sequencing
Morphology
- Trichosporon: cream, dry, wrinkled colonies; hyphae that break into arthroconidia.
- Rhodotorula: mucoid orange to salmon-colored colonies (carotenoid pigment).
- Saccharomyces: oval budding yeasts with ascospores, similar to Candida but without true hyphae.
Transmission
- Endogenous: colonization of skin, gut or airway that enters the blood through mucosal damage.
- Central venous catheters (Rhodotorula especially).
- Probiotic capsules opened at the bedside contaminate hands and catheters (Saccharomyces); spread between patients by hands has caused outbreaks.
Reservoir: Soil, water, food and human skin and gut; Probiotic products (Saccharomyces boulardii)
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- Biofilm on catheters and devices.
- Intrinsic resistance: Trichosporon and Rhodotorula are not killed by echinocandins, so they can break through while patients receive them.
- Trichosporon cell wall shares an antigen with Cryptococcus, which explains a positive cryptococcal antigen test.
Diseases it causes
- Trichosporon fungemia and disseminated infection in hematologic malignancy and neutropenia, with skin nodules and high mortality. Febrile neutropenia →
- Catheter-related fungemia by Rhodotorula, and probiotic-associated Saccharomyces fungemia in ICU and immunosuppressed patients. Sepsis and septic shock →
- Trichosporon also causes white piedra on hair and summer-type hypersensitivity pneumonitis in healthy people.
Clinical picture
- Suspect them when a yeast grows from blood in a patient already receiving an echinocandin.
- In a Latin American review of rare yeasts, Trichosporon asahii was the most common species and fungemia the main presentation, with high crude mortality.
- Leukemia, central venous catheters, cancer, surgery and broad-spectrum antibiotics are the usual backgrounds.
Diagnosis
- Blood cultures; identification to species by mass spectrometry or ITS sequencing (biochemical tests can mislabel them).
- Colony color is a clue: orange-salmon suggests Rhodotorula.
- Trichosporon can make the cryptococcal antigen and galactomannan tests positive.
Treatment
Trichosporon: voriconazole is preferred; amphotericin B, echinocandins and flucytosine are not reliable. Rhodotorula: amphotericin B (with or without flucytosine); it resists echinocandins and azoles. Saccharomyces: amphotericin B or an echinocandin, stop the probiotic. Removing the catheter is part of treatment.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Careful central-line care and early removal.
- Avoiding probiotics with live yeast in critically ill and immunosuppressed patients, and never opening capsules near catheters.
- Hand hygiene to prevent spread between patients.
Test yourself
Think of the answer, then tap the question to see it.
A neutropenic patient on an echinocandin develops fungemia with a yeast that forms arthroconidia. What is the likely genus and preferred drug?
Trichosporon; voriconazole is preferred because echinocandins and amphotericin B are unreliable.
Which rare yeast forms orange to salmon colonies and is almost always catheter-related?
Rhodotorula.
What is the main risk factor for Saccharomyces fungemia?
Use of probiotics containing Saccharomyces (S. boulardii), especially with a central catheter.
Why can Trichosporon cause a false-positive cryptococcal antigen test?
Its cell wall shares a polysaccharide antigen with Cryptococcus.
Connections
← Back to the group: Yeasts and yeast-like fungi
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Rare fungal infectious agents: a lurking enemy (F1000Research (PMC), 2017); Rare Yeasts in Latin America: Uncommon Yet Meaningful (Journal of Fungi (PMC), 2023).
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Representative model, for educational purposes only.