Athlete's foot overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
- Athlete's foot (tinea pedis) is a fungal infection of the skin that causes scaling, flaking, and itching of affected areas.
- It mainly affects the soles, skin over toes, interdigital spaces and nails. [1]
- It is typically transmitted in moist areas where people walk barefoot, such as showers or bathhouses.
- Athlete's foot is caused infection with a dermatophyte fungus.
- Although the condition typically affects the feet, it can spread to other areas of the body, including the groin.
- Athlete's foot can be prevented by good hygiene, and is treated by a number of pharmaceutical and other treatments.
Historical Perspective
- The Oxford English Dictionary documents written usage of the term in 1928 (1928 Lit. Digest 22 December. 16/1), which seems to undercut the claim by W. F. Young, Inc. that the term "athlete's foot" was originated, rather than simply popularized, as part of an advertising campaign for Absorbine Jr. during the 1930s.[2]
Pathophysiology
- Athlete's foot is caused by a parasitic fungus and is a communicable disease.[3]
- It is typically transmitted in moist environments where people walk barefoot, such as showers, bath houses, and locker rooms.[4][5][3]
- It can also be transmitted by sharing footwear with an infected person, or less commonly, by sharing towels, socks, footwear or clothes with an infected person.
Pathology
- Majority of the cases of athlete's foot are caused by Trichophyton rubrum. But other organisms such as Epidermophyton floccosum, Trichophyton interdigitale, Trichophyton mentagrophytes are also implicated in development of tinea pedis.
- Trichophyton tonsurans has been identified as a cause of tinea pedis infections in children. [6]
- The fungi cause breakdown of superficial skin through secretion of enzymes called keratinises which dissolve keratin.[7]
- The fungal cell wall of dermatophytes also contain mannans which diminish the body's inflammatory response by decreasing antigen presenting and processing.[8]
- It is interesting to note thatTrichophyton rubrum often causes chronic and long drawn infection due to increased production of mannans which decrease the turnover and proliferation of keratinocytes.[9]
- The dermatophytes thrive in a moist and damp environment. Maceration, superficial tears in the skin and chronic occlusive footwear usage for long periods of time increase the chance of getting infected.
- Several innate factors such as transferrin, beta globulins and sebum have a growth-inhibitory effect on these fungi. Transferrin, particularly the unsaturated form inhibits growth by binding iron which is required for growth and propagation of dermatophytes. [10]
- A poor immune system such as in immunocompromised individuals also is a predilection for infection with tinea spp.[11]
Diagnosis
Physical Examination
Athlete's foot can usually be diagnosed by visual inspection of the skin, but where the diagnosis is in doubt direct microscopy of a potassium hydroxide preparation (known as a KOH test) may help rule out other possible causes, such as eczema orpsoriasis.[12] A KOH preparation is performed on skin scrapings from the affected area. The KOH preparation has an excellent positive predictive value, but occasionally false negative results may be obtained, especially if treatment with an anti-fungal medication has already begun.
Other Diagnostic Studies
A Wood's lamp, although useful in diagnosing fungal infections of the hair (Tinea capitis), is not usually helpful in diagnosing tinea pedis since the common dermatophytes that cause this disease do not fluoresce under ultraviolet light. However, it can be useful for determining if the disease is due to a non-fungal afflictor.
Treatment
Medical Therapy
There are many conventional medications (over-the-counter and prescription) as well as alternative treatments for fungal skin infections, including athlete's foot. Important with any treatment plan is the practice of good hygiene. Several placebo controlled studies report that good foot hygiene alone can cure athlete's foot even without medication in 30-40% of the cases.[13] However, placebo-controlled trials of allylamines and azoles for athlete’s foot consistently produce much higher percentages of cure than placebo.[14]
Prevention
The fungi that cause athlete's foot can live on shower floors, wet towels, and footwear. Athlete's foot is caused by a fungus and can spread from person to person from shared contact with showers, towels, etc. Hygiene therefore plays an important role in managing an athlete's foot infection. Since fungi thrive in moist environments, it is very important to keep feet and footwear as dry as possible.
References
- ↑ Ely JW, Rosenfeld S, Seabury Stone M (2014). "Diagnosis and management of tinea infections". Am Fam Physician. 90 (10): 702–10. PMID 25403034.
- ↑ The of W. F. Young, Inc. and Absorbine at the Absorbine website.
- ↑ 3.0 3.1 Causes of athlete's foot, at WebMD
- ↑ "Athlete's foot". Mayo Clinic Health Center.
- ↑ [1] Risk factors for athlete's foot, atWebMD
- ↑ Hiruma J, Ogawa Y, Hiruma M (2015). "Trichophyton tonsurans infection in Japan: epidemiology, clinical features, diagnosis and infection control". J Dermatol. 42 (3): 245–9. doi:10.1111/1346-8138.12678. PMID 25736317.
- ↑ Sharifzadeh A, Shokri H, Khosravi AR (2016). "In vitro evaluation of antifungal susceptibility and keratinase, elastase, lipase and DNase activities of different dermatophyte species isolated from clinical specimens in Iran". Mycoses. 59 (11): 710–719. doi:10.1111/myc.12521. PMID 27291045.
- ↑ Weitzman I, Summerbell RC (1995). "The dermatophytes". Clin Microbiol Rev. 8 (2): 240–59. PMC 172857. PMID 7621400.
- ↑ Dahl MV, Grando SA (1994). "Chronic dermatophytosis: what is special about Trichophyton rubrum?". Adv Dermatol. 9: 97–109, discussion 110-1. PMID 8060745.
- ↑ King RD, Khan HA, Foye JC, Greenberg JH, Jones HE (1975). "Transferrin, iron, and dermatophytes. I. Serum dematophyte inhibitory component definitively identified as unsaturated transferrin". J Lab Clin Med. 86 (2): 204–12. PMID 1151148.
- ↑ Dai Y, Xia X, Shen H (2019). "Multiple abscesses in the lower extremities caused by Trichophyton rubrum". BMC Infect Dis. 19 (1): 271. doi:10.1186/s12879-019-3897-3. PMC 6425592. PMID 30894136.
- ↑ del Palacio, Amalia. "Trends in the treatment of dermatophytosis" (PDF). Biology of Dermatophytes and other Keratinophilic Fungi: 148–158. Retrieved 2007-10-10. Unknown parameter
|coauthors=ignored (help) - ↑ Over-the-Counter Foot Remedies (American Family Physician)
- ↑ Crawford F, Hollis S (18 July 2007). "Topical treatments for fungal infections of the skin and nails of the foot" (Review). Cochrane Database of Systematic Reviews (3): Art. No.: CD001434. doi:10.1002/14651858.CD001434.pub2.