Microsporum ferrugineum: Introduction, Morphology, Pathogenicity, Lab Diagnosis, Treatment, Prevention, and Keynotes


Microsporum ferrugineum is a species of dermatophytic fungus that belongs to the genus Microsporum. Dermatophytes are a group of fungi that are capable of infecting and colonizing the outer layers of the skin, hair, and nails, causing various dermatophytosis or “ringworm” infections in humans and animals.

Microsporum ferrugineum specifically is known for causing a type of dermatophytosis called tinea capitis, which is a fungal infection that affects the scalp and hair shafts. It’s commonly found in various regions around the world and can be transmitted through direct contact with an infected person, animal, or contaminated objects like combs, brushes, or hats. The infection can manifest as itchy, scaly, red patches on the scalp, and in severe cases, hair loss can occur.

Effective treatment for Microsporum ferrugineum infections typically involves antifungal medications, either topical or oral, depending on the severity of the infection. It’s important to properly diagnose and treat tinea capitis to prevent its spread and further complications. If you suspect you have a fungal infection, it’s best to consult a medical professional for accurate diagnosis and appropriate treatment.


Microsporum ferrugineum, like other species in the Microsporum genus, has distinctive morphological characteristics that can help in its identification. Here are some key features of the morphology of M. ferrugineum:

Microsporum ferrugineum colony morphology on dermatophyte test medium (DTM) showing a waxy glabrous, convoluted thallus with a cream to buff coloured surface and no reverse pigment
Fig. Microsporum ferrugineum colony morphology on dermatophyte test medium (DTM) showing a waxy glabrous, convoluted thallus with a cream to buff coloured surface and no reverse pigment
  1. Macroconidia: These are the larger spores produced by the fungus. In Microsporum ferrugineum, the macroconidia are typically numerous, spindle-shaped, and multicellular. They have smooth walls and are often characterized by their size and shape. The ends of the macroconidia can be rounded or slightly pointed.
  2. Microconidia: Microconidia are smaller spores that are produced in addition to macroconidia. They are usually oval or spherical in shape and can be single-celled or multicellular. These microconidia are often found near the base of the macroconidia or at the tips of conidiophores (specialized structures that produce conidia).
  3. Conidiophores: Conidiophores are the structures that bear the conidia (both macroconidia and microconidia). They can arise from the fungal hyphae and are often unbranched or sparsely branched.
  4. Color: The name “Microsporum ferrugineum” suggests a reddish or rust-colored appearance. This refers to the characteristic orange-brown to reddish-brown color of the colony when grown on culture media.
  5. Texture: The colony texture of M. ferrugineum can vary from velvety to powdery, depending on the growth conditions and the medium it’s cultivated on.
  6. Hyphae: The fungal hyphae of M. ferrugineum are septate, meaning they are divided into compartments by cross-walls called septa.
  7. Chlamydospores: These are thick-walled, resting spores that may be produced by some strains of Microsporum ferrugineum. They can contribute to the survival of the fungus in adverse conditions.
Microsporum ferrugineum in LPCB taese mount of culture microscopy showing typical bamboo hyphae and lacking production of both microconidia and macroconidia
Fig. Microsporum ferrugineum in LPCB taese mount of culture microscopy showing typical bamboo hyphae and lacking production of both microconidia and macroconidia


Microsporum ferrugineum is a pathogenic fungus that can cause various dermatophytosis or “ringworm” infections in humans. The pathogenicity of M. ferrugineum lies in its ability to invade and colonize the outer layers of the skin, hair, and nails, leading to a range of clinical presentations and symptoms.

The primary dermatophytosis caused by Microsporum ferrugineum is tinea capitis, which is a fungal infection that affects the scalp and hair shafts. This infection is more common in children but can also affect adults. The pathogenic process involves the following steps:

  1. Colonization: M. ferrugineum spores, particularly macroconidia and microconidia, come into contact with the skin or hair. They adhere to the keratinized tissue, which provides a nutrient source for the fungus.
  2. Invasion: The fungus penetrates the outer layers of the skin, specifically the stratum corneum, and can also invade the hair shafts. It secretes enzymes that help break down keratin, allowing it to use the keratin as a nutrient source.
  3. Inflammatory Response: As the fungus colonizes and grows within the skin, it triggers an inflammatory response from the host’s immune system. This response can lead to the characteristic symptoms of itching, redness, and scaling associated with tinea capitis.
  4. Clinical Presentation: In the case of tinea capitis caused by Microsporum ferrugineum, affected individuals may develop round or irregularly shaped patches of scaling, inflamed skin on the scalp. These patches can be itchy and sometimes painful. Hair loss within the affected areas is also common, and the hair shafts might break off close to the scalp, leading to a “black dot” appearance.
  5. Transmission: The infection can spread from person to person through direct contact, sharing of personal items like combs or hats, or by contact with contaminated surfaces.

Lab Diagnosis

The laboratory diagnosis of Microsporum ferrugineum infections, like other dermatophytosis or “ringworm” infections, involves several methods to identify the causative fungus and confirm the infection. Here are the common laboratory techniques used for diagnosing Microsporum ferrugineum infections:

  1. Direct Microscopic Examination: Microscopic examination of skin, hair, or nail samples taken from the affected area is often the initial step in diagnosis. The samples are treated with potassium hydroxide (KOH) to dissolve keratin and reveal the fungal elements. Under a microscope, the characteristic fungal structures such as hyphae, conidia (macroconidia and microconidia), and sometimes chlamydospores can be observed.
  2. Fungal Culture: Fungal culture involves growing the fungus from the collected samples on specialized growth media. Sabouraud’s agar is commonly used for dermatophyte cultures. The culture allows the fungus to grow and produce characteristic colonies, which can aid in identification. Microsporum ferrugineum colonies often display an orange-brown to reddish-brown color on culture.
  3. Macroscopic Examination of Colonies: The appearance of the fungal colonies on culture media can provide important clues for identifying M. ferrugineum. The texture, color, and growth rate of the colonies are observed.
  4. Microscopic Examination of Colonies: Similar to direct examination of patient samples, microscopic examination of the grown colonies can reveal the characteristic fungal structures. This includes observing the shape and size of macroconidia, microconidia, and other structures.
  5. Molecular Techniques: Polymerase chain reaction (PCR) and DNA sequencing can be used to genetically identify M. ferrugineum. This method provides highly accurate identification and can differentiate between various Microsporum species.
  6. Wood’s Lamp Examination: While not specific to Microsporum ferrugineum, a Wood’s lamp (ultraviolet light) examination can sometimes help visualize some dermatophyte infections. In the case of Microsporum species, the infected hairs may fluoresce green under the Wood’s lamp.


The treatment of Microsporum ferrugineum infections, particularly tinea capitis (scalp infection), involves antifungal medications aimed at eradicating the fungal infection. The choice of treatment depends on the severity of the infection, the patient’s age, and other individual factors. Here are the common treatment options for M. ferrugineum infections:

  1. Oral Antifungal Medications:
    • Griseofulvin: This is an oral antifungal medication that has been traditionally used for treating tinea capitis. It works by inhibiting fungal growth and preventing the fungus from spreading. It’s often effective against Microsporum species.
    • Terbinafine: Another oral antifungal, terbinafine, is also used to treat tinea capitis. It is generally well-tolerated and has shown good efficacy against Microsporum infections.
  2. Topical Antifungal Medications:
    • Ketoconazole: Topical ketoconazole shampoos or creams can be used for milder cases of tinea capitis. However, oral medications are often more effective for scalp infections.
    • Ciclopirox: Topical ciclopirox solutions or creams may be prescribed for certain cases of tinea capitis, especially if the infection is limited to the superficial layers of the scalp.
  3. Adjunctive Measures:
    • Hygiene and Cleaning: Keeping the affected area clean and dry can help prevent further fungal growth and spread.
    • Avoid Sharing Personal Items: To prevent the spread of the infection to others, individuals with tinea capitis should avoid sharing combs, brushes, hats, and other personal items.
    • Environmental Cleaning: Thoroughly cleaning and disinfecting items that come in contact with the affected person’s scalp can help prevent reinfection or spreading the infection to others.

It’s important to note that treatment duration can vary depending on the severity of the infection and the chosen antifungal medication. Complete eradication of the infection is essential to prevent recurrence and complications. Additionally, follow-up visits to a healthcare professional are recommended to monitor progress and ensure that the infection has been successfully treated.


Preventing Microsporum ferrugineum infections, as well as other dermatophytosis or “ringworm” infections, involves adopting good hygiene practices and being mindful of potential sources of infection. Here are some preventive measures to consider:

  1. Personal Hygiene:
    • Keep your skin and scalp clean and dry.
    • Regularly wash your hair with a mild shampoo.
    • Avoid sharing personal items like combs, brushes, hats, towels, and hair accessories, especially in settings where close contact is common.
  2. Avoid Contact with Infected Individuals or Animals:
    • Refrain from direct contact with individuals or animals that have visible fungal infections.
    • If you have a fungal infection, take precautions to prevent spreading it to others.
  3. Proper Foot Care:
    • If you have tinea pedis (athlete’s foot), keep your feet clean and dry, especially between the toes.
    • Wear moisture-wicking socks and well-ventilated shoes.
    • Avoid walking barefoot in public areas like communal showers or locker rooms.
  4. Maintain Clean Living Spaces:
    • Regularly clean and disinfect shared spaces like bathrooms, showers, and swimming pool areas.
    • Wash and disinfect gym equipment before and after use.
  5. Avoid Excessive Moisture:
    • Fungi thrive in warm, moist environments. Dry your skin thoroughly after bathing, swimming, or any activity that causes sweating.
  6. Choose Appropriate Footwear:
    • Wear sandals or open-toed shoes in public locker rooms, showers, and pool areas.
    • Choose shoes made from breathable materials to reduce moisture buildup.
  7. Regularly Examine Pets:
    • If you have pets, regularly inspect their fur and skin for signs of infection.
    • Consult a veterinarian if you suspect your pet has a fungal infection.
  8. Educate Children:
    • Teach children about the importance of personal hygiene and avoiding contact with potentially infected individuals or animals.
  9. Prompt Treatment:
    • If you suspect you have a fungal infection, seek prompt medical attention for accurate diagnosis and appropriate treatment.
    • Follow your healthcare provider’s instructions for treatment and hygiene to prevent the spread of infection.
  10. Follow Healthcare Guidelines:
  • If you’re undergoing treatment for a fungal infection, follow your healthcare provider’s recommendations regarding medication use and hygiene practices.


Here are some keynotes on Microsporum ferrugineum:

  1. Species Classification: M. ferrugineum is a species of dermatophytic fungus belonging to the genus Microsporum.
  2. Pathogenicity: It is pathogenic and primarily causes tinea capitis, a fungal infection affecting the scalp and hair.
  3. Clinical Presentation: In tinea capitis cases caused by Microsporum ferrugineum, patients may develop round or irregularly shaped patches of scaling, inflamed skin on the scalp. Hair loss within affected areas is common, leading to a “black dot” appearance.
  4. Infection Transmission: The infection can spread through direct contact with an infected individual, contaminated personal items, or surfaces.
  5. Laboratory Diagnosis:
    • Direct microscopic examination: Detect characteristic fungal structures like hyphae, macroconidia, and microconidia.
    • Fungal culture: Cultivate the fungus on specialized media to observe colony characteristics.
    • Molecular techniques: PCR and DNA sequencing for accurate species identification.
  6. Treatment:
    • Oral antifungal medications like griseofulvin or terbinafine are often prescribed for severe cases of tinea capitis.
    • Topical antifungal creams, shampoos, or lotions may be used for milder infections.
    • Treatment duration varies based on severity and patient factors.
  7. Prevention:
    • Maintain personal hygiene: Keep skin, hair, and nails clean and dry.
    • Avoid sharing personal items: Prevents transmission from infected individuals.
    • Proper foot care: Prevent tinea pedis (athlete’s foot) by keeping feet dry and wearing breathable footwear.
  8. Environmental Factors: Microsporum ferrugineum thrives in warm, moist environments, making proper drying essential to prevent infection.
  9. Species Identification: Accurate identification requires expertise in mycology due to similarities with other Microsporum species.
  10. Children’s Vulnerability: Tinea capitis is more common in children, but adults can also be affected. Educating children about hygiene can help reduce transmission.
  11. Medical Consultation: Suspected fungal infections should be assessed by healthcare professionals for accurate diagnosis and appropriate treatment.

Further Readings

  1. Medical Journals and Articles:
    • Search for scientific articles and research papers related to Microsporum ferrugineum in medical journals such as the Journal of Clinical Microbiology, Journal of Investigative Dermatology, and Medical Mycology.
    • PubMed (https://pubmed.ncbi.nlm.nih.gov/) is a comprehensive database for medical and scientific literature.
  2. Dermatology Textbooks:
    • Dermatology textbooks like “Fitzpatrick’s Dermatology in General Medicine” and “Andrews’ Diseases of the Skin” provide in-depth information on dermatological conditions, including fungal infections.
  3. Mycology Textbooks:
    • Mycology-specific textbooks such as “Medical Mycology: A Self-Instructional Text” by Alex Alexiou and “Color Atlas and Text of Clinical Medicine” by H. C. Gugnani offer detailed insights into fungal infections and their diagnosis.
  4. Online Medical Resources:
  5. Dermatology Organizations:
    • Websites of dermatology organizations such as the American Academy of Dermatology (https://www.aad.org/) and the British Association of Dermatologists (https://www.bad.org.uk/) often have resources and guidelines on fungal infections.
  6. Mycology Societies:
    • Mycology societies like the Mycological Society of America (https://msafungi.org/) may offer resources related to fungal infections and research.
  7. Academic Institutions:
    • Websites of universities and medical schools often host research publications, articles, and resources related to fungal infections and dermatology.

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