Dermatomycosis and Dermatophytes

1. KARTHIK REDDY C A
MSC 3rd SEM MICROBIOLOGY
Reg No – NP20AL61
NRUPATHUNGA UNIVERSITY
BANGALORE - 01
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2. INTRODUCTION
Dermatomycosis is one of the most frequent fungal
infections of skin and skin appendages, which
encompass nails and hair.
It is a mycotic diseases of skin caused by a few mycetes :
Dermatophytes and some opportunistic fungi.
These fungal infections impair superficial layers of the
skin, hair and nails.
Dermatomycosis mainly caused by filamentous fungi.
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3. DERMATOPHYTES
• Dermatophytes are a common label for a group of fungus of arthrodermaceae
that commonly causes skin disease in animals and humans.
• These anamorphic mold genera are : Microsporum, Epidermophyton and
trichophyton.
• These cause infections of skin, hair, and nails, obtaining nutrients from
keratinized material.
• The organisms colonize the keratin tissues causing inflammation as the host
responds to metabolic byproducts.
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4. EPIDERMIOLOGY
Dermatophyte fungi are the most common fungal infections world wide.
Dermatophytosis was first described by David Gruby, a Hungarian
physician in 1841.
Before Gruby, various scientist described lesions which were ring like and
were thought to be infective.
The description of lesions dates back to the Roman era.
Around 1890, Raimond sabouraud advance knowledge of
dermatomycology by studying extensively into the taxonomy, morphology
and treatment of dermatophytes even classifying these fungal agents into 4
genera.
Dermatophytosis has been prevalent since early 1900’S at which time
ringworm was treated with compounds of mercury or sometimes sulfur or
iodine.
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5. MORPHOLOGY
• Hyphae of dermatophytes are long, undulant and branching.
• Many septa are present along the length of hyphae.
• Hyphae break at the septa into barrel shaped arthrospores.
CULTURALCHARACTERS
• In culture, dermatophytes form conidiophores with resulting microconidia and macroconidia.
• Genera and Species identification is based on gross characteristic of colony and microscopic
morphology of conidia.
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6. CHARACTERISTICS
• Dermatophytes are a group of about 40 related fungi that belongs to three genera:
1. Microsporum
2. Trichophyton
3. Epidermophyton
• They are restricted to Non- viable skin because most are unable to grow at 37°C or in the presence of
Serum.
• Many species have particular keratinase, Elastase and other enzymes which make them host specific.
• Several are capable of sexual reproduction – produce ascospores. Thus belongs to genus
Arthroderma.
• In skin, they produce hyaline, septate, branching hyphae or chains of arthroconidia.
• Epidermophyton Flucosum is the only pathogen in this genus which produces macroconidia.
• They are highly contagious and frequently transmitted by exposure to shed scale, nails, hairs
containing hyphae and conidia.
• They remain viable for long periods on fomites.
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7. SYMPTOMS
o The first symptom is a distinctive skin rash on the face, eyelids,
chest, nails, cuticle areas, knees or elbows.
o The rash is patchy and usually a bluish to purple colour.
o May also get muscle weakness that gets work over weeks or
months. This muscle weakness usually starts in neck, arms, or
hips and can be felt on both sides of body.
o Other symptoms are –
o Muscle pain and tenderness
o Swallowing problems and lung problems
o Hard calcium deposits underneath, the skin which is mostly seen
in children.
o Fatigue, unintentional weight loss, fever.
There is a subtype of dermatomyositis that includes the rash but
not muscle weakness. This is know as amyopathic dermatomyositis.
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8. LABORATORYDIAGNOSIS
• MRI is used to observe abnormal muscles.
• Electromyography ( EMG ) to record electrical impulses that control
muscles.
• Blood analysis to check the levels of muscle enzymes and
autoantibodies, which are antibodies that attack normal cells.
• A muscle biopsy to look for inflammation and other problems
associated with the disease in a sample of muscle tissue.
• A skin biopsy to look for changes caused by the disease in a skin
sample.
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9. TREATMENT
• Tinea corpora ( body ), tinea manus (hands), tinea cruris ( groin ), tinea pedis ( foot ) and tinea
facie ( face ) can be treated topically.
• Tinea unguiem ( nails ) usually will require oral treatment with terbinafine, itraconazole, or
griscofulvin.
• Tinea capitis ( scalp ) must be treated orally, as the medication must be present deep in the hair
follicles to eradicate the fungus. Griseofulvin is given orally for 2 to 3 months.
• Tinea pedis is usually treated with topical medicines, like ketoconazole or terbinafine and pills
or with medicine that contains miconazole, clotrimazole or tolnaftate.
• Antibiotics may be necessary to treat secondary bacterial infections that occur in addition to the
fungus.
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10. Epidermophyton
• Epidermophyton floccosum is a filamentous dermatophytic fungus known to cause
skin and nail infections in humans.
• It is an anthropophilic dermatophyte hence it is transmissible from one individual to
another.
• Common infections caused by dermatophytes include tinea pedis (athlete’s foot),
tinea crusis, tinea corporis, and onychomycosis.
• It is the third most common cause of Tinea pedis (athletes foot).
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11. Habitat of Epidermophyton floccosum
•It is an ascomycete and therefore it has a worldwide distribution.
•It commonly occurs in tropical and subtropical regions.
•It does not live in the soil.
•It is common in North America and Asian countries.
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12. Morphological and Cultural Characteristics of E. Floccosum
o Growth in basic mycological medium, Epidermophyton floccosum grows slowly, producing greenish-
brown or khaki-colored colonies, with a suede-like surface.
o The colonies have a centralized occurrence that is raised and folded, a flat periphery, and submerged
fringe growth.
o Mature cultures produce white pleomorphic tufts of mycelium with a deep yellowish-brown reverse
pigment.
o Microscopic observation shows smooth, thin-walled macroconidia occurring in clusters on the hyphal
threads.
o They are also observed to be filamentous fungus, with septate and hyaline hyphae.
o The hyphae contain smooth, whin-walled, clavate, club-shaped, clusters macroconidia.
o Chlamydospores are also formed in mature/old cultures.
o They do not form microconidia.
o The distinction of Epidermophytes floccosum from the other dermatophytes
(Microsporum and Trichophyton)is that they do not form microconidia and they form macroconidia
which are shorter, wide, and smooth.
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13. Figure: Pleomorphism of E. floccosum. A: Overview of the Wild-Type surface; B: Revise
side of wild-type; C: Overview of pleomorphic E. floccosum; D: Revise side of
pleomorphic E. floccosum.
Image Source: Creative Biolabs
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14. Pathogenesis and clinical manifestations of Epidermophyton floccosum
o Epidermophyton floccosum is transmitted from person-to-person via skin contact, causing cutaneous
and subcutaneous infections on the skin, and nails.
o As a dermatophyte, it causes dermatophytosis affecting the keratinized regions in the body including
hair, skin, and nails.
o Symptoms vary depending on the site of the body affected, such as:
o Hair infections are Tinea capitis, Tinea barbae characterized by invasion of hair follicles (without
perforation), hair loss (ectothrix), and/or hair breakage (endothrix).
o On the skin, the formation of lesions is commonly characterized by circular or annular ringworm
infections (tinea corporis).
o As an anthropophilic fungus, it does not cause inflammations or hypersensitivity.
o They have also been associated with causing keratitis of the eye.
o Infection of the nails is commonly characterized by discoloration, dystrophy, hyperkeratosis, and
onycholysis.
o Manifestations occur several weeks after contracting the fungus.
o Disseminated and invasive disease infections are rare.
o However, invasive Epidermophyton floccosum infection has been documented in persons with Behcet’s
syndrome.
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15. Laboratory Diagnosis of Epidermophytonfloccosum
Specimen: Skin scrapings, pus/lesion biopsies, hair scarpings
Microscopic Examination
10-20% KOH Wet mount for observation of smooth, thin-walled, wide macroconidia.
Cultural Examination
 Growth in Sabouraud Dextrose Agar with cycloheximide and chloramphenicol to suppress mold and
bacterial growth and observation of growth in 3 weeks. The colonies formed are greenish-brown or
khaki-colored with a suede-like surface.
 The colonies also appear raised and folded at the center with a flattened periphery.
 Extended growth produces white colonies showing pleomorphism in mycelial growth, producing deep
yellow to brown mycelium on reverse pigmentation.
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16. Molecularcharacterization and differentiation
 Use of PCR-Restriction Fragment Length Plormophism (PCR-RFLP) is used to distinguish the 12
species that cause dermatophytosis infections.
 Real-time PCR is also used to identify Epidermophyton floccosum after fungal lysis
Treatment of Epidermophytonfloccosuminfections
 Tinea capitis is tretaed with griseofulvin or oral azoles (ketoconazole, itraconazole, and
voriconazole).
 Tinea corporis, tinea crisis, tinea pedis, and tinea manuun are treated tropically using naftifine,
terbinafine, butenafine, clotrimazole, econazole, ketoconazole, miconazole, oxiconazole,
sulconazole, cyclopyrox, and tolnaftate.
 Nail infections, topical therapy is normally unsuccessful, and therefore, the use of systemic oral
therapy for a prolonged period is advised
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17.  A Text book of Microbes and Diseases of Man – W C DEB.
 Text book of Medical microbiology – H L CHOPRA.
 Fritz H. Kayser (2005). Medical microbiology. Thiemeverlag.
 https://www.healthline.com/health/dermatomycosis.
 https://microbnotes.com/Epidermophyton-floccosum.
 https:www.slideshare,net/AnkurVashishtha4/dermatophytes.
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