Molds and dermatophytes !
- Fungi
Filamentous fungi: environmental molds that attack the immunosuppressed, and dermatophytes that feed on the keratin of skin, hair and nails.
Updated 2026-11-01
What they are
Molds grow as hyphae, branching filaments. Aspergillus and the Mucorales are in air and soil and cause severe invasive infection when neutrophils are missing or ketoacidosis is present. Dermatophytes invade only the keratin layer and cause tinea; the agents of chromoblastomycosis are pigmented molds that enter through a wound.
What they share
- Grow as hyphae (filaments), also inside the body
- Septate hyphae branching at acute angles suggest Aspergillus; broad, nearly aseptate hyphae at right angles suggest Mucorales
- Dermatophytes use keratin and do not invade living tissue
- Pigmented (dematiaceous) molds carry melanin in their wall
Microorganisms in this group
- Aspergillus fumigatusA mold of air, dust and soil; it causes allergy in asthma, fungus balls in old cavities and invasive pneumonia in patients without neutrophils.Exam priority: medium
- Mucorales (Rhizopus, Mucor)Soil molds that invade vessels and destroy tissue very fast, above all in diabetic ketoacidosis: from the sinuses into the orbit and brain.Exam priority: medium
- Dermatophytes (Trichophyton, Microsporum, Epidermophyton)Fungi that feed on keratin and cause tinea of the skin, scalp, groin, feet and nails. Spread by contact with people, animals or objects.Exam priority: medium
- Agents of chromoblastomycosis (Fonsecaea and other pigmented fungi)Dark fungi of soil and wood that enter through a wound, usually on a farmer's leg, and form slow-growing wart-like plaques.For completeness
Test yourself
Think of the answer, then tap the question to see it.
What separates Aspergillus hyphae from Mucorales hyphae on a biopsy?
Aspergillus: thin, septate, branching at acute angles. Mucorales: broad, with few or no septa, branching at nearly right angles.
Why do dermatophytes almost never cause deep infection?
They feed on keratin and stay in the stratum corneum, hair and nails.
Which molds in the group are pigmented and form muriform bodies?
The agents of chromoblastomycosis, such as Fonsecaea pedrosoi.
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Clinical Overview of Aspergillosis (CDC, 2024); Clinical Overview of Mucormycosis (CDC, 2024); Clinical Overview of Ringworm (CDC, 2024); Chromoblastomycosis (WHO, 2023).
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Representative model, for educational purposes only.