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Microbiology · Other fungi of clinical interest

Talaromyces marneffei !

  • Fungus
  • For completeness

A fungus from Southeast Asia that causes disseminated infection in people with advanced AIDS, with skin bumps dented in the centre.

Updated 2026-11-01

Also called: Penicillium marneffei (old name), talaromycosis, penicilliosis

At a glance

Shape
Mould at 25 °C with a red pigment that diffuses into the agar; at 37 °C, yeast-like cells that divide by fission with a cross wall
Family
Trichocomaceae (order Eurotiales)
Type
Thermally dimorphic fungus: mould in the environment, intracellular yeast in tissue
Stain
Wright, Giemsa, PAS or Grocott: yeasts inside macrophages, with a central septum

Morphology

  • In tissue: oval cells inside macrophages, like Histoplasma, but with a central septum instead of budding.
  • In culture at room temperature: a mould colony with a wine-red pigment that diffuses into the medium.

Transmission

  • Probably by inhaling conidia from the environment.
  • Bamboo rats carry the fungus, but there is no evidence of direct spread from rat to person.
  • Not spread from person to person.

Reservoir: Soil of endemic areas; Bamboo rats

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • Dimorphism: switching to a yeast at body temperature lets it live inside macrophages.
  • It spreads through blood and the reticuloendothelial system when cell-mediated immunity is badly depressed.

Diseases it causes

Clinical picture

  • Fever, weight loss, cough, lymphadenopathy and hepatosplenomegaly.
  • Painless skin papules on the face and neck, often with central umbilication (like molluscum contagiosum).
  • In people without HIV it involves the mouth, throat, lung, liver and bone more often.

Diagnosis

  • Culture of blood, bone marrow or skin: a mould with red pigment at room temperature.
  • Smear or biopsy of skin or marrow: intracellular yeasts with a cross septum.
  • Antigen tests and PCR in specialised centres.

Treatment

Antifungals: amphotericin B for induction, then itraconazole; voriconazole or posaconazole are alternatives. In people with HIV, antiretroviral therapy is a central part of care.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

Prevention

  • Azole prophylaxis (mainly itraconazole) for severely immunosuppressed people living in endemic areas.
  • Early diagnosis and treatment of HIV.

Test yourself

Think of the answer, then tap the question to see it.

How is Talaromyces told apart from Histoplasma on a bone-marrow smear?

Both are yeasts inside macrophages, but Talaromyces divides by fission with a cross septum and Histoplasma by budding.

What culture feature is classic for Talaromyces marneffei?

At room temperature it grows as a mould that releases a red pigment diffusing into the agar.

In which patient should talaromycosis be suspected?

A person with advanced HIV who lived in or travelled to Southeast Asia, southern China or India and has fever, umbilicated papules and hepatosplenomegaly.

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Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Talaromycosis (Penicilliosis) Basics | Talaromycosis | CDC (CDC, 2024).

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Representative model, for educational purposes only.