biology

Trichosporon asteroides

Trichosporon asteroides is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Trichosporon asteroides rather than just read about it. In short: Trichosporon asteroides is an asexual basidiomycetous fungus first described from human skin but now mainly isolated from blood and urine. T. asteroides is a hyphal fungus with a characteristically yeast-like appearance due to the presence of slimy arthroconidia.

Key takeaways

Trichosporon asteroides belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Trichosporon asteroides to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Trichosporon asteroides from memory before moving on to harder problems.

Reference excerpt

Trichosporon asteroides is an asexual basidiomycetous fungus first described from human skin but now mainly isolated from blood and urine. T. asteroides is a hyphal fungus with a characteristically yeast-like appearance due to the presence of slimy arthroconidia. Infections by this species usually respond to treatment with azoles and amphotericin B.

History and taxonomy Trichosporon asteroides was isolated from lesion of male chin skin by Rinchin in Bern in 1926 and named in the genus, Parendomyces. T. asteroides was later reevaluated by Masao Ota and transferred to the genus Trichosporon as T. asteroides. Ota noted that its hyphae were more sparsely branched than other species in Trichosporon, and it lacked the ability to ferment glucose, maltose, sucrose and fructose. Molecular phylogenetic study has since supported the placement of T. asteroides in the genus Trichsporon. T. asteroides was determined to be conspecific with Fissuricella filamenta on the basis of DNA/DNA reassociation. Modern classifications support the placement of this species within the order Trichosporonales.

Growth and morphology Trichosporon asteroides grows in a range of media including in the presence of the antifungal agent, cycloheximide. Colonies of T. asteroides grown on Sabouraud agar appear white with a brain-like texture, reaching a diameter of 10 mm after 10 days growth at 25 °C (77 °F). Colonies have a radially furrowed outer zone and matt appearance that is not powdery like the related species, T. asahii. Antibodies produced by infected patients can also be used to differentiate T. asahii and T. asteroides in disease. Weak growth is seen at 37 °C (99 °F) but is absent at higher temperatures. T. asteroides can be distinguished from related Trichosporon species by its ability to utilize D-galactose, L-rhamnose, erythritol and L-arabinitol.

Physiology and pathogenesis Trichosporon asteroides does not ferment glucose, maltose, sucrose or fructose, a feature common to all Trichosporon species. T. asteroides causes trichosporonosis, causing deep-seated, mucosa-associated, superficial, and systematic infections including blood. This species is one of the three most common Trichosporon species isolated in clinical settings. The fungus is sometimes recovered from specimens of blood, urine, and aspiration fluid, vaginal mucosa, male perigenital skin area, and catheters. The first record of this agent in a systemic infection involved a bloodstream infection. Main types of latent infection include fungemia, urinary tract infections, peritonitis, endocarditis, arthritis, esophagitis, meningitis, brain abscess, splenic abscess, and uterine infections. Allergies and systemic infections can also be caused by this fungus particularly in immunosuppressed people. Recently, T. asteroides was implicated in a case of kerion celsi, a rare, highly inflammatory scalp infection seen mainly in children. This fungus is rarely encountered in zoonotic infections and has never been shown to cause disease in insects. However, T. asteroides was isolated from multifocal, irregularly raised skin lesions on a female bottle-nosed dolphin, Tursiops truncatus, in Japan. In the absence of cultures and molecular biological analysis, the agent was initially suspected to be Paracoccidioides ceti, a worldwide causative agent of Paracoccidioidomycosis in dolphins.

Treatment Azole antifungals are often used as a front-line therapy in trichosporonosis. Resistance to amphotericin, flucytosine, fluconazole, and itraconazole have been described. Echinocandins, as a group, are ineffective against Trichosporon species. Triazoles show better in vitro and in vivo antifungal activity than amphotericin B, while voriconazole also has excellent in vitro activity against Trichosporon asteroides. Combination therapy regimens such as voriconazole and amphotericin B are also effective in serious infections. Fluconazole has been used successfully in subcutaneous and deep infections.

References

Illustrations

Worked examples

Example 1 — a first encounter with Trichosporon asteroides

Start with the simplest possible case. Write down what Trichosporon asteroides claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Trichosporon asteroides before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Trichosporon asteroides ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Trichosporon asteroides

In research: Trichosporon asteroides appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Trichosporon asteroides in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Trichosporon asteroides is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fungal pathogens of humans, Fungi described in 1926, Fungus species, so understanding it makes those chapters shorter.
In everyday life: Look for Trichosporon asteroides outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Trichosporon asteroides in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Trichosporon asteroides means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Trichosporon asteroides out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Trichosporon asteroides in simple terms?

Why does Trichosporon asteroides matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Trichosporon asteroides?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Trichosporon asteroides.