Luciano Schiazza M.D.
Mycotic infections of the skin are dermatosis commonly detected by GP’s and dermatologists. They are frequent cutaneous infections caused by dermatophytes.
Dermatophytes are a group of fungi responsible of infections on the superficial layer of the skin, nails and hair.
The nosological classification of dermatophytes relies mainly on all criteria, with reference to the anatomic striken area:
HOW THE DISEASE SPREADS
The dermatophytic infection of the skin comes from:
direct or indirect infection among humans, animals and humans or man and environment
self-contagious infection caused by transferring patologic material from one to another part of the body of the same person, often caused by scratching
In the first case lesions are normally one or a few in the uncovered areas of the body (face, forearms, legs); in the second case there are multiple lesions in the covered parts of the body.
Indirect infection can be caused by hair, skin squamae, combs, brushes, backrests in and public areas, bed linen, hats, towels, hotel carpets, underwear, changing rooms, shower plates, etc. Generally speaking with infectious material.
Tinea corporis is an infection of hairless skin, it normally affects uncovered parts of the body, (neck, face, hands, forearms) common all over the world. It comes across both sexes of any age, but children are the most exposed.
Lesions generally come out 1 to 3 weeks after contagion, caused by
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It can therefore be caused by:
direct or indirect contact with an infected human or animals (cats, cricetuses, rabbits)
garment, carpets, rugs, contaminated objects
auto-infection caused by lesions, sometimes not evident, in other area
Children are the most exposed, presumably for the particular tendency to infection of children’s skin and for childhood habits.
The skin becomes affected in the inoculation site and lesion becomes evident after an incubation period of 1-3 weeks.
It starts with annular, scaly and itchy ringworms that grow centrifugally. Growing it takes an oval or circular shape particularly scaly at the annular margin.
Two kinds of lesion characterize tinea corporis:
Annular lesions – see above
Vesicular – vesicles containng light color liquid appear ireegularly or immediately close to the rash.
Lesions are generally localized in one area. Scratching often spreads in other areas due to the infectuous material accumulated under the nails
The therapy of tinea corporis constist of topical or oral treatment. In general it responds well to topical antifungal treatment, however, if there are several ringworm lesion or if lesions are extensive, oral medications can be used.
Tinea cruris is an acute or chronic infection of the groin, perineum and perianal region. It is characterized by intense pruritus.
It presents with sharply demarcated lesions wth a raised erythematous margin and thin, dry epidermal scaling.
It spreads throught the world, especially in tropical regions where warmth and humidity favour maceration in the inguinal region.
The infection is definitely more frequent in men. Tinea cruris involves the genito-crural area, sometimes unilateral. Hair never get infected
Crowded places such as gym lockers and dormitories favour the rapid diffusion of the infection.
The predominant aspect of the disease is intense pruritus.
The acute infection begins with an area in the groin fold about a half-inch across, usually on both sides. The area may enlarge, and other sores may develop in no particular pattern. The rash appears as raised red plaques (platelike areas) and scaly patches with sharply defined borders that may blister and ooze.
Usually bilateral, not symmetric. In fact it is observed a major diffusion in the lower part of the left tigh, due to the lower extension of the scrotum on the left side.
Making the diagnosis
Attention has to be paid to the possible coexistance with occulted or neglected tinea pedis. In suspect cases laboratory tests can confirm the diagnosis.
In general tinea cruris responds well to topical treatment. However, due to the sensitivity of the groin area, particular attention is recommended in order to avoid irritation.
If there are several, or extensive lesions, oral antifungal treatment can be used (see tinea corporis chapter)
Tinea manuum is a fungal infection of the skin on the hands. It generally occurs in the palms and between fingers.
It is more frequent in men than women, aged between 11 and 40. It often affects one hand only, while one or both feet can simultaneously prsent the desease. You can therefore find 1 hand and both feet, or 2 hands and a foot.
It manifests in different ways: on the palm that is thickened, dry and scaly, or with edges that have bumps and circular rashes.
Topic treatment is generally sufficient, the dermatologist might however, prescribe oral treatment when necessary.
It is a skin infection of the bottom of the foot and between the toes.
It is the most common human fungal infection and the most prevalent of infectious diseases. It spreads in all the Continents and affects 30 – 70% of the world population.
This infection is related to footware and is considered to be a “new” dermatophytoses in that it began in association with use of footware. More occlusive shoes are associated with higher chances of having tinea pedis. The warmth and humidity of interdigital spaces favour the growth of fungi.
It normally occurs in the interdigital space between the 4° and 5° toe.
It spreads through direct contact in swimming pools and health clubs. Dermatophytes are on the floor of hotel rooms, locker rooms, saunas, homes, shower plates, maths, towels and underwear. The rate of infection increases in relation with the number of people using the facilities.
Wearing closed and rubber/plastic shoes, or the use of non transpirant socks, increases temperature and hyperhidrosis which cause maceration and increases the skin PH fvouring the growths of parassites and fungi.
Contagion is always indirect: contact of bare feet with infected areas (swimming pools, floors, etc.) The spread of infection is due to maceration and non transpiration .
30 – 70% of adults might be infected with tinea pedis at some time in their lives. Males are more prone to infection than females.
The most common is interdigitale (moist peeling irritable skin between the toes) most often in the cleft between the fourth and the fifth toes. Most probably prolongued use of occlusive footwear with a resulting complications of hyperhidrosis and maceration are the cause of the disease.
The infected area is covered by dry, scaly white, macerated skin, which frequently stink.
Prevention of tinea pedis
Use non occlusive footware
if not possible, change shoes every 2-3 days and put the shoes in the open air put antifungal powder in the shoes every day
use cotton socks
avoid to walk with bare feet in swimming pools
after bathing dry well feet, especially interdigital areas
See tinea corporis
Tinea unguium or ringworm is due to a fungal infection (dermatophyte) Onychomycosis is an infection of the nail caused by mould or yeast (not dematophyte)
Contagion might occur within the family, working (vegetable or flowers farming) in public areas such as swimming pools and health clubs, using infected tools such as clippers or files. It may also spread to the nails from other affected areas of the body.
Dermatophytes need particular conditions to spread in the nail tissue:
macerating action of sweat
Excessive length of nails
Poor blood circulation
There are general, or local factors that can favour the mycotic infection:
reduced growth of the nail
precedent nail alteration
pre-existing pathological conditions
systemic factors such as diabetes and cardio vascular diseases
lifestyle. Sports, for instance, not only favour micro, or traumas of the big toe, but also increase the contagion risk due to environmental presence of dermatophytes in such areas.
Two most common:
1) White superficial onychomicosys
The toenails are usually affected. It is quite common and usually not detected because asymptomatic and not easily visible.
The superficial layers of the nail form well delineated opaque “white islands” with a diametre of 1 mm or less, easy to take off.
They can appear on any place of the nail plate. They tend to coalesce to involve the entire nail plate.
The infection tends to become chronic and it can therefore persist for years
2) Distal subungual onychomycosis
The most common form of tinea unguium is distal subungual onychomycosis, which can also be distal and lateral.
It may develop in toenails, fingernails or both. The infection of finger nails, usually monolateral, is generally associated with the toe nails infection (one hand, two feet syndrome).
There are two types:
Onychosis, in which the contagion comes from the lateral nail margin. There is a progressive infection of the nail bed and the underside of the nail plate and white-yellowish striae appear. The area of most intense yellow colour corresponds to a most elevated number of dermatophytes.
In other cases (hyperkeratosis) the infection provokes high subungual hyperkeratosis. This weakens and thickens the nail, which can separate from the nail bed and become friable and brittle extending to the area of the lunula. The colour of the ungula lamina can become greysh-yellow or greysh-green.
Oral therapy is recommended
Tinea capitis is the name used for infection of the scalp with a dermatophyte fungus. Although common in children up to puberty, tinea capitis is less frequently seen in adults. The reason is not quite clear, but it might be related with the production of sebum (that inhibits fungi invasion of the hair) in the period of puberty. Highly contagious, it easily spreads in schools causing epidemics.
Overcrowded areas and poor personal hygiene favour the transmission of the disease. Contagion generally comes from direct contact with affected individuals. Rats are another source of contagion. The organism remains viable on hats, combs, brushes, head rests, etc, for over a year.
There are three kinds of tinea capitis:
microsporic tinea capits
tricophytic tinea capits
favosa tinea capitis
Is the most frequent and sporadic (transmission from cats) or epidemic, (inter-human in communities).
Large scaly patches, like dandruff but usually with moth-eaten hair loss (2-3 mm long).
capitis Many small patches. Inflammation is contained. Hair are broken under the follicular orifice (the surface looks invaded by black heads), different size of hair is observed. More patches converge in a figure or as diffused alopecia.
Favus, or tinea favosa
Favus is characterized by the occurrence of dense masses of fungi in the ostium follicular area, forming yellowish cup shaped crusts called scutula. The scutulum develops at the surface of a hair follicle. Hair look discoloured and “dusty”.
Sometimes scutula merge and form large smelly patches that may affect the whole scalp. Hair gradually thin and break to a few centimetres from the scalp.
Tinea barbae is a superficial dermatophyte infection that is limited to the bearded areas of the face and neck and occurs almost exclusively in older adolescent and adult males. The clinical presentation of tinea barbae includes inflammatory, deep, kerionlike plaques and noninflammatory superficial patches resembling tinea corporis or bacterial folliculitis
There are two kind of lesions:
Superficial, similar to tinea corporis;
It mainly occurs in rural areas to farmers and animal handlers in contact with infected animals.
In urban areas it may occur to people infected with tinea in other areas of the body such as: tinea pedis, tinea cruris, onychomychosis.
There are two kinds:
The superficial infection looks like tinea corporis with central patches, particularly scaly at the vesicle-pustular margin
The deep infection is more frequent. It may be very red and inflamed, thick nodules covered with pustules. The nodules may ooze bloody pus.
Sometimes the infection can be aggravated by bacteria: in this case regional lymphadenopathy, malaise and fever will occur.
The upper lip is normally not affected when bacteria are not involved.
Oral treatment will have to be associated with antimycotic cream and compresses (to remove scaly patches), for topic treatment only will not penetrate in the deepest parts of the hair follicles.
It is a superficial infection of the glabrous skin. It therefore excludes the hairy areas of male adults.
The infection is often acquired from pets (cats, rabbits, dogs, horses, hamsters, ovines).
In other cases contagion may occur from other areas of the body such as feet or groin.
Tinea faciei occurs worldwide. It affects male and female adults, while male children and teenagers are more affected than females.
Tinea faciei is often misdiagnosed among other mycotic infection because of the occurrence of symptoms such as itch, burning sensation intolerance to the sunlight.
often resembles psoriasis on the cheek, but presents as erythematous, edematous plaques with an elevated, scaled border, especially after exposure to zoophilic or geophilic fungus. By contrast, anthropophilic fungus, such as Trichophyton
It presents as erythematous scaly anular patches.
Topic therapy is recommended.
The suspect mycotic infection has to be tested in order to certified.
The tests allow:
The presence of the fungus
The insulation of the fungus
The identification of gender and species
The detection of the fungus is possible through the direct microscopic test. It is the most rapid and reliable to detect spore and filaments.
The insulation of the fungus through culture that detects the different kind of fungi.
The identification of the fungi species is performed through the observation of the aspects of the colony. Microscopic evaluation will follow.