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Athlete's Foot |
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 Athlete's foot or tinea pedis is a fungal
infection of the skin of the foot, usually between the toes, caused by parasitic
fungi.
Causes
The body normally hosts a variety of saprotrophic microorganisms, including
bacteria and fungi. Some of these are useful to the body. Pathogenic or disease
causing organisms or the overgrowth of saprotrophic ones can multiply rapidly
and cause infection. Athlete's foot is a layman's description of a skin fungal
infection. Fungal infections of the skin are called dermatophytosis.
Dermatophytes may be spread from other humans (anthropophilic), animals (zoophilic)
or may come from the soil (geophilic). Anthropophillic dermatophytes are
restricted to human hosts and produce a mild, chronic inflammation. Zoophilic
organisms are found primarily in animals and cause marked inflammatory reactions
in humans who have contact with infected cats, dogs, cattle, horses, birds, or
other animals. Geophilic species are usually recovered from the soil but
occasionally infect humans and animals. They cause a marked inflammatory
reaction, which limits the spread of the infection and may lead to a spontaneous
cure but may also leave scars. Infections or infestations occur when
dermatophytes grow and multiply in the skin.
Growth Environment
Growth of the athlete's foot fungus is promoted by a dark, warm, moist
environment such as that found inside shoes. The fungi persist for a long time
in the environment, facilitating transmission of the disease in communal areas
such as locker rooms and showers.
Symptoms
Athlete's foot causes scaling, flaking and itching of the affected skin.
Blisters and cracked skin may also occur, leading to exposed raw tissue, pain,
swelling, and inflammation. The infection can be spread to other areas of the
body, such as the armpits, knees, elbows, and the groin, and usually is called
by a different name once it spreads (such as jock itch or tinea cruris for an
infection of the skin of the groin).
Treatment
The infection is often treated with topical antifungal agents such as miconazole,
itraconazole, terbinafine and a keratolytic such as salicylic acid. Topical
agents only clear the infection about 30% of the time and provide mycologic
cures (absence of organisms) less than 15% of the time. The time line for cure
may be long, often 45 days or longer. However, because the itching associated
with the infection subsides quickly, patients may not complete the courses of
therapy prescribed. Washing socks, underwear and bed clothes at 60C or 140F will
also help prevent any re-infection.
Some topical applications such as Castellani's Paint, often used for intertrigo,
work well but in small selected areas. Carbol Fuscin Red dye used in this
treatment like many other vital stains is both fungicidal and bacteriocidal;
however, because of the staining are cosmetically undesirable. For many years
gentian violet was also used for inter-digital and other bacterial and fungal
infections.
Oral treatment with griseofulvin was begun early in the 1950s. Because of the
tendency to cause liver problems and to provoke aplastic anemia the drugs were
used cautiously and sparingly. Over time it was found that those problems were
due to the size of the crystal in the manufacturing process and microsize and
now ultramicrosize crystals are available with few of the original side effects.
Oral treatment provides long lasting mycologic cure.
If the fungal invader is not a dermatophyte but a yeast, other medications such
as fluconazole may be used. Typically diflucan is used for candidal vaginal
infections moniliasis but has been shown to be of benefit for those with
cutaneous yeast infections as well. The most common of these infections occur in
the web spaces (intertriginous) and at the base of the fingernail or toenail.
The hall mark of these infections is a cherry red color surrounding the lesion
and a yellow thick pus.
Undecylenic acid (Castor oil derivative) is an effective fungicide for fungal
skin infections such as athlete's foot.
Remedies and Folklore
Traditional remedies for athlete's foot include Tea Tree Oil (Melaleuca Oil) or
crocodile oil in a topical application on the affected area. Users report
instant relief from itching allowing lesions to heal. Proponents of urine
therapy claim that urine is very effective at killing athlete's foot. Urea, the
"active ingredient" in urine, is already used in many drugs and treatments made
by pharmaceutical companies to treat athlete's foot. This controversial
treatment method recommends urinating on the infected area once a day in the
shower. According to supporters, urine therapy not only kills existing fungi, it
prevents new fungi from growing in the infected area.
One biochemist states that urea is only used to soften the outer layers of skin
so that antifungal drugs can reach fungi below the surface, and that the urea
must be concentrated and applied for a long period of time in order to be
effective. According to another article about high-concentration urea cream, the
compound is used to "dissolve proteins and [as a] denaturant. The ability of
urea to macerate [tissue] has been attributed to a 'proteolytic effect', but
others attribute the maceration to the hydrating properties of urea." This use
requires a high concentration of urea, up to 40%, and extended exposure. Urea
itself without the presence of an additional antifungal drug is not referred to
in scholarly literature as having antifungal properties. Thus, it is unlikely
that urinating on one's feet in the shower will significantly improve a case of
athlete's foot.
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