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Microbiology · Molds and dermatophytes

Aspergillus fumigatus !

  • Fungus
  • Exam priority: medium

A mold of air, dust and soil; it causes allergy in asthma, fungus balls in old cavities and invasive pneumonia in patients without neutrophils.

Updated 2026-11-01

Also called: Aspergillus

At a glance

Shape
Thin septate hyphae branching at acute angles
Family
Aspergillaceae (Eurotiales)
Type
Hyaline mold (filamentous fungus)
Stain
Silver (GMS) and PAS in tissue; lactophenol blue in culture
Size
Hyphae about 3–6 µm wide

Morphology

  • Thin hyphae with regular septa, branching at acute angles (about 45°)
  • In culture: a conidiophore with a vesicle bearing chains of conidia
  • Fast-growing blue-green colonies
  • Tolerates high temperatures

Transmission

  • Inhaling conidia present in air, dust, soil, plants and building works
  • Not spread from person to person or from animals to people

Reservoir: Soil, decaying plant matter, dust and building materials

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • Small conidia that reach the alveolus
  • Invasion of blood vessels with thrombosis and tissue infarction
  • Toxins such as gliotoxin, which depresses immune function
  • A. flavus makes aflatoxin, linked to liver cancer (via contaminated food)

Diseases it causes

  • Aspergillosis: allergic bronchopulmonary (asthma, cystic fibrosis), aspergilloma in old cavities and invasive aspergillosis in the immunosuppressed Aspergillosis →

Clinical picture

  • Allergic bronchopulmonary aspergillosis: hard-to-control asthma, eosinophilia, high IgE and central bronchiectasis
  • Aspergilloma: a fungus ball in an old cavity (for example, from tuberculosis); hemoptysis
  • Invasive: fever unresponsive to antibiotics, pleuritic pain and nodules with a halo on CT in neutropenia or transplant
  • Allergic or invasive sinusitis

Diagnosis

  • Galactomannan in serum or bronchoalveolar lavage
  • Beta-D-glucan (supportive, non-specific)
  • Chest CT: nodules with a halo in invasive disease
  • Biopsy with septate acute-angle hyphae; culture (grows in a few days); PCR
  • Susceptibility testing when azole resistance is suspected

Treatment

Invasive disease: broad-spectrum azoles (voriconazole first choice; isavuconazole as an alternative) or lipid amphotericin B. Allergic disease: corticosteroids with or without itraconazole. Aspergilloma: surgery in selected cases. Azole resistance in A. fumigatus is emerging, linked to agricultural fungicide use.

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

In Pharmacology:

Prevention

  • Protected environment with HEPA filtration for patients with profound neutropenia or transplant
  • Dust control during hospital building works
  • Azole prophylaxis (for example, posaconazole) in high-risk patients

Test yourself

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

What do Aspergillus hyphae look like on biopsy?

Thin, septate and branching at acute angles.

Which fungal antigen is measured in serum or lavage to support invasive aspergillosis?

Galactomannan.

Which form of aspergillosis grows in an old tuberculosis cavity and presents with hemoptysis?

Aspergilloma, the fungus ball.

What is the antifungal of choice for invasive aspergillosis?

Voriconazole (a triazole); isavuconazole and lipid amphotericin B are alternatives.

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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: Aspergillosis Basics (CDC, 2024); Clinical Overview of Aspergillosis (CDC, 2024); WHO releases first-ever list of health-threatening fungi (WHO, 2022).

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Representative model, for educational purposes only.