Skin Conditions | May 30, 2015 | Author: The Super Pharmacist
Tinea is an infection of the skin caused by fungi called dermatophytes. The term tinea can be made more specific by grouping it with the name of the infection’s location. Almost all tinea infections are caused by one of three dermatophytes, namely, Epidermophyton, Trichophyton, or Microsporum. Certain dermatophytes are more likely to affect certain regions of the body. For example, Trichophyton rubrum is the most common cause of athlete’s foot (tinea pedis), jock itch (tinea cruris), tinea unguium, and tinea corporis. Nevertheless, other dermatophytes might be responsible for these conditions as well. While Trichophyton rubrum is the most common cause of athlete’s foot, the condition can also be caused by Trichophyton mentagrophytes and Epidermophyton floccosum. Therefore, treatment should target all three major types of dermatophytes, when possible.
Tinea infections are quite common, however, these skin infections can be confused with other fungal infections, bacterial skin infections, autoimmune conditions, rashes, and drug reactions. Antifungal treatments will have no effect on any skin condition other than those caused by a fungus. Likewise, treatment with corticosteroids can make infections (including Microsporum canis) worse. A physician can identify dermatophyte infection by subjecting an extracted hair or skin scrapings to potassium hydroxide and examining them under a microscope. Whether this is done in routine clinical practice is another matter.
Numerous topical and oral treatments are available to kill dermatophyte infections. Many belong to a group called “azoles.” Azoles kill dermatophytes by breaking down their cell membranes and preventing them from reproducing.
Topical azole treatment is usually the first line treatment for most dermatophyte infections. Topical treatment is usually required for 2 weeks or more and continues until the infection is gone and the skin has healed. While topical azoles are often used first, better scientific data exists to support the use of non-azole treatments, specifically topical terbinafine and topical naftifine. This is not to say that terbinafine or naftifine are necessarily better than the azoles, it simply means that better clinical studies have been done for the former two agents. Ciclopirox olamine, griseofulvin, butenafine, and oral terbinafine may also be used.
Corticosteroids do not directly kill or disrupt the dermatophytes, rather they block the inflammation caused by the fungal infection. Accordingly, corticosteroids are not a sole treatment for tinea, rather a corticosteroid is sometimes combined with an antifungal. Topical corticosteroids stop skin redness and itchiness that often accompany tinea, while the antifungal attacks the infection. There is some evidence to suggest that topical corticosteroid/antifungal combination drugs help speed up healing. On the other hand, corticosteroids may actually interfere with the healing process in some cases, especially with certain dermatophyte infections (e.g. Microsporum canis). Therefore, corticosteroid/antifungal combinations should only be used when the diagnosis has been confirmed with a potassium hydroxide preparation or culture.
Various home remedies have been suggested for the treatment of tinea infections. These remedies have not been evaluated in clinical studies, so it is difficult to make firm recommendations about their use. One of the more commonly suggested treatments for athlete’s foot is antiperspirant spray. This remedy may be theoretically helpful because fungal infections seed and spread in warm, moist environments. Conversely, antiperspirants help keep regions dry that would otherwise harbor dermatophytes. However, this effect could also be achieved by talc/baby powder. It is more likely that antiperspirants help prevent recurrence of tinea rather than treat active infections.
Since tinea is a superficial skin infection, it is reasonable to conclude that substances applied to the skin could disrupt or even kill dermatophytes. As such, people have used various household chemicals to treat tinea. While substances such as bleach, isopropyl alcohol, vinegar, and concentrated hydrogen peroxide are helpful in destroying dermatophytes on surfaces, the concentrations and number of applications required to kill the dermatophytes will likely cause a breakdown in skin, increased aging, increased redness, and the potential for more serious infection. On the other hand, using these household chemicals to thoroughly wash bed linens and other potential reservoirs of dermatophytes is important to preventing recurrence.
Tinea infections are quite common in individuals who are immunocompromised. Likewise, instead of being simple surface infections, the tinea may invade deeper into the skin or hair follicle. Topical treatments may not successfully treat immunocompromised individuals. Therefore, first line treatment for tinea in immunocompromised individuals is usually an oral antifungal medication. Moreover, corticosteroids should be avoided since these substances further suppress the immune system.
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