Fungal Skin Infections PDF

FUNGAL SKIN INFECTIONS Dr. Ibrahim Al-Adham Taken from Handbook of Nonprescription Drugs > Chapter 41. 1  FUNGAL SKIN INFECTIONS Fungal skin infections, or dermatomycoses, are among the most common cutaneous disord...

FUNGAL SKIN INFECTIONS Dr. Ibrahim Al-Adham Taken from Handbook of Nonprescription Drugs > Chapter 41. 1  FUNGAL SKIN INFECTIONS Fungal skin infections, or dermatomycoses, are among the most common cutaneous disorders. Dermatomycoses are often referred to as ringworm because their characteristic lesions are ring shaped with clear centers and red, scaly borders. However, these lesions can vary from the ring form and may present as single or multiple lesions that range from mild scaling to deep granulomas (inflamed, nodular lesions). 2  FUNGAL SKIN INFECTIONS Fungal infections are usually superficial and can involve the hair, nails, and skin. The term TINEA refers exclusively to dermatophyte infections. Most often, tinea infections are named according to the area of the body that is affected Scalp [tinea capitis], Groin [tinea cruris], Body [tinea corporis], Feet [tinea pedis], and Nails [tinea unguium]. 3 The trauma affords infecting fungi the opportunity to invade the outer layers of the skin. In addition, wearing socks and shoes exacerbates the problem by impeding the dispersion of heat and the evaporation of moisture, both of which facilitate fungal growth. In contrast, individuals who most often use footwear that allows the feet to remain cool and dry (e.g., sandals) are less likely to develop tinea pedis. Nonporous shoe material increases temperature and hydration of the skin, which interferes with the barrier function of the stratum corneum. Similarly, sweating or wearing wet clothing for long periods of time can predispose individuals to the development of tinea corporis and tinea cruris. 4 Other predisposing factors for the development of tinea infections include diabetes mellitus and other diseases associated with immune system depression, use of immunosuppressive drugs, impaired circulation, poor nutrition and hygiene, occlusion of the skin, and warm, humid climates. 5  PATHOPHYSIOLOGY OF FUNGAL SKIN INFECTIONS Tinea infections are caused by three genera of pathogenic fungi: Trichophyton, Microsporum, and Epidermophyton. Fungal transmission can occur through contact with infected people, animals, soil, or fomites. Dermatophytes are classified according to their habitat: Anthropophilic (humans), Zoophilic (animals), and Geophilic (soil). Most tinea infections are caused by person to person contact with individuals infected with anthropophilic dermatophytes 6 Dermatophytid infestations remain within the stratum corneum. Resistance to the spread of infection seems to involve both immunologic and non-immunologic mechanisms. For example, the presence of a serum inhibitory factor (SIF) appears to limit the growth of dermatophytes beyond the stratum corneum. SIF is not an antibody but a dialyzable, heatlabile component of fresh sera. It appears that SIF chelates the iron that dermatophytes need for continued growth. 7  CLINICAL PRESENTATION OF FUNGAL SKIN INFECTIONS The clinical spectrum of tinea infections ranges from mild itching and scaling to a severe, exudative inflammatory process characterized by denudation, fissuring, crusting, and/or discoloration of the affected skin. 8  DIFFERENTIATION OF FUNGAL SKIN INFECTIONS AND SKIN DISORDERS WITH SIMILAR PRESENTATION Criterion Fungal Skin Infections Contact Dermatitis Bacterial Skin Infection Location On areas of the body where Any area of the body exposed Anywhere on the body excess moisture accumulates, to the allergen/irritant; hands, such as the feet, groin area, face, legs, ears, eyes, and scalp, and under the arms anogenital area involved most often Signs Presents either as soggy Presents as a variety of lesions: Presents as a variety of lesions malodorous, thickened skin; raised wheals (red, swollen from macules to pustules to acute vesicular rash; or fine mark left on flesh by pressure), ulcers with redness surrounding scaling of affected area with fluid filled vesicles, or both the lesion; lesions are often varying degrees of warmer than surrounding, inflammation; cracks and unaffected skin fissures may also be present Symptoms Itching and pain Itching and pain Irritation and pain 9  DIFFERENTIATION OF FUNGAL SKIN INFECTIONS AND SKIN DISORDERS WITH SIMILAR PRESENTATION Criterion Fungal Skin Infections Contact Dermatitis Bacterial Skin Infection Quantity/ Usually localized to one Affects all areas of exposed Usually localized to one severity region of the body but can skin but does not spread region of the body but can spread spread Timing Variable onset Variable onset from Variable onset immediately after exposure to 3 weeks after contact Cause Superficial fungal infection Exposure to skin irritants or Superficial bacterial infection allergens Modifying Treated with nonprescription Treated with topical Treated with prescription factors astringents, antifungals, and antipruritics, skin protectants, antibiotics nondrug measures to keep the astringents, and nondrug area clean and dry measures to avoid reexposure 10  TINEA PEDIS Clinically, tinea pedis has four accepted variants; two or more of these types may overlap. The most common is the chronic intertriginous type, characterized by fissuring, scaling, or maceration in the interdigital spaces; malodor; pruritus; and/or a stinging sensation on the feet (see Color Plates, photograph 27). Typically, the infection involves the lateral toe webs, usually between either the fourth and fifth or the third and fourth toes. From these sites, the infection may spread to the sole or instep of the foot but rarely to the dorsum. Warmth and humidity aggravate this condition; consequently, hyperhidrosis (excessive sweating) becomes an underlying problem and must be treated along with the dermatophyte infestation. 11  TINEA PEDIS The second variant of tinea pedis foot is known as the chronic papulosquamous pattern. It is usually found on both feet and is characterized by mild inflammation and diffuse, moccasinlike scaling on the soles of the feet. Tinea unguium of one or more toenails may also be present and may continue to fuel the infection. The toenails must first be cured with oral drug therapy, such as itraconazole, ketoconazole, or terbinafine, or they must be removed surgically to rid the area of the offending fungus. 12  TINEA PEDIS The third variant of tinea pedis is the vesicular type, usually caused by Trichophyton mentagrophytes var. interdigitale. Small vesicles or vesicopustules are observed near the instep and on the midanterior plantar surface. Skin scaling is seen on these areas as well as on the toe webs. This variant is symptomatic in the summer and is clinically quiescent during the cooler months 13  TINEA PEDIS The acute ulcerative type is the fourth variant of tinea pedis. It is often associated with macerated, denuded, weeping ulcerations on the sole of the foot. Typically, white hyperkeratosis and a pungent odor are present. This type of infection, which is complicated by an overgrowth of opportunistic, gramnegative bacteria such as Proteus and Pseudomonas, has been called a “dermatophytosis complex,” and it may produce an extremely painful, erosive, purulent interspace that can impede the patient’s ability to walk 14 Tinea pedis seen in the interdigital space between the fourth and fifth digits. This is the most common area to see tinea pedis. 15  TINEA UNGUIUM Nails affected by tinea unguium gradually lose their normal shiny luster and become opaque. If left untreated, the nails become thick, rough, yellow, opaque, and friable. The nail may separate from the nail bed if the infection progresses secondarily to subungual hyperkeratosis. Ultimately, the nail may be lost altogether. Subungual debris also provides an excellent medium for the growth of opportunistic bacteria and other microorganisms, which can lead to further infectious complications. 16  TINEA CORPORIS Tinea corporis may have a diverse clinical presentation. Most often, the lesions, which involve glabrous (smooth and bare) skin, begin as small, circular, erythematous, scaly areas. The lesions spread peripherally, and the borders may contain vesicles or pustules. Infected individuals may also complain of pruritus. Tinea corporis can occur on any part of the body. However, the location of the infection can provide clues to the type of infecting dermatophyte. For example, zoophilic dermatophytes often infect areas of exposed skin such as the neck, face, and arms. In contrast, infections secondary to anthropophilic dermatophytes often occur in occluded areas or in areas of trauma. 17 Tinea corporis on the shoulder of this young girl. This is a very typical annular pattern and the cat on the sweatshirt might be a clue to an infected pet at home spreading a Microsporum dermatophyte to its owner. Note the concentric rings with scaling, erythema, and central sparing 18  TINEA CRURIS Tinea cruris is more common in males and occurs on the medial and upper parts of the thighs and the pubic area. The lesions have welldemarcated margins that are elevated slightly and are more erythematous than the central area; small vesicles may be seen, especially at the margins. Acute lesions are bright red, and chronic cases tend to have more of a hyperpigmented appearance; fine scaling is usually present. This condition is generally bilateral with significant pruritus; however, the lesions usually spare the penis and scrotum. This characteristic can help to distinguish tinea cruris from candidiasis, which also causes lesions in these areas. Pain may also be present during periods of sweating or when the skin becomes macerated or infected by a secondary microorganism. 19 A 54-year-old man with tinea cruris and corporis for decades despite multiple treatments with oral antifungal medications. His cultures show T. rubrum sensitive to all the typical oral antifungal medications, but his tinea never completely clears. He does not have a known immunodeficiency but his immune system appears not to recognize the T. rubrum as foreign. 20  TINEA CAPITIS Clinically, tinea capitis may present as one of four variant patterns, depending on the causative dermatophyte. In non-inflammatory tinea capitis, lesions begin as small papules surrounding individual hair shafts. Subsequently, the lesions spread centrifugally to involve all hairs in their path. Although there is some scaling of the scalp, little inflammation is present. Hairs in the lesions are a dull gray color and usually break off above the scalp level. The inflammatory type of tinea capitis produces a spectrum of inflammation, ranging from pustules to kerion formation. Kerions are weeping lesions whose exudate forms thick crusts on the scalp. In addition to fever and pain, individuals with this type of tinea capitis may experience a higher degree of pruritus. Regional lymph nodes may also be enlarged. 21  TINEA CAPITIS The black dot variety of tinea capitis was named for the appearance of infected areas of the scalp. The location of arthrospores on the hair shaft causes hairs to break off at the level of the scalp, leaving black dots on the scalp surface. Hair loss, inflammation, and scaling with this type of tinea capitis range from minimal to extensive. Therefore, this variant is especially challenging to diagnose. The favus variant of tinea capitis typically presents as patchy areas of hair loss and scutula (yellowish crusts and scales). Ultimately, these lesions can coalesce to involve a major portion of the scalp. If left untreated, this condition can lead to secondary bacterial infections, scalp atrophy, scarring, and permanent hair loss 22  PITYRIASIS VERSICOLOR (TINEA VERSICOLOR) Hyper- and hypopigmented scaly patches characterize pityriasis versicolor, which is also known as tinea versicolor. On dark skin the lesions often appear as hypopigmented areas, while on light skin they are slightly erythematous or hyperpigmented. The expression of infection is promoted by heat and humidity. The typical lesions consist of oval scaly macules, papules, and patches concentrated on the chest, shoulders, and back but only rarely on the face or distal extremities. It is caused by yeasts of the Malassezia genus. Topical treatment usually is adequate unless there is extensive involvement, recurrent infections, or failure of topical therapy. 23 Large areas of pink tinea versicolor on the shoulder in a cape-like distribution 24 Patches of hypopigmentation across the back caused by tinea versicolor in a young Latino man. 25 TREATMENT OF FUNGAL SKIN INFECTIONS Treatment Goals: The goals of treating fungal skin infections are to: (1) provide symptomatic relief, (2) eradicate existing infection, and (3) prevent future infections. 26  GENERAL TREATMENT APPROACH In many instances, patients can effectively selftreat tinea pedis, tinea corporis, and tinea cruris with non-prescription topical antifungals and non- pharmacologic measures. However, individuals with tinea unguium or tinea capitis should be referred to a primary care provider for treatment. 27 Patients who want to improve the appearance of the nail during prescription treatment of tinea unguium can use Fungal Nail Revitalizer to reduce nail discoloration and to smooth out the thick, rough nail. This product contains calcium carbonate (a strong alkali) and urea (a protein denaturant) to debride nail tissue. The patient should apply the cream over the entire surface of the infected nail, scrub this area for at least 1 minute with the provided nailbrush, and then wash and dry the nail completely. For optimum results, this procedure should be performed daily for 3 weeks. Patients should be advised that this product will improve only the appearance of the nails and that it will not treat the tinea infection. 28  PHARMACOLOGIC THERAPY Butenafine hydrochloride, clioquinol, clotrimazole, haloprogin, miconazole nitrate, terbinafine hydrochloride, tolnaftate, and various undecylenates are considered safe and effective for nonprescription use in the treatment of fungal skin infections. These agents are labeled for treatment of athlete’s foot, jock itch, and body ringworm. The recommended treatment period is a minimum of 1- 4 weeks. 29  CLOTRIMAZOLE AND MICONAZOLE NITRATE Topical clotrimazole and miconazole nitrate are imidazole derivatives that demonstrate fungistatic/fungicidal activity (depending on concentration) against Trichophyton mentagrophytes, Trichophyton rubrum, Epidermophyton floccosum, and Candida albicans. These agents act by inhibiting the biosynthesis of ergosterol and other sterols and by damaging the fungal cell wall membrane, thereby altering its permeability and resulting in the loss of essential intracellular elements. FDA classifies clotrimazole 1% and miconazole nitrate 2% as safe and effective for topical nonprescription use in treating tinea pedis, tinea cruris, and tinea corporis. Clotrimazole and miconazole nitrate are applied once in the morning and once in the evening. For athlete’s foot and ringworm, these drugs should be applied twice daily for 4 weeks. For jock itch they should be applied twice daily for 2 weeks. 30  TERBINAFINE HYDROCHLORIDE Topical terbinafine hydrochloride 1% was reclassified as a nonprescription medication in 1999. This antifungal agent inhibits squalene epoxidase, a key enzyme in fungi sterol biosynthesis. This action results in a deficiency in ergosterol and a corresponding accumulation of squalene within the fungal cell, causing fungal cell death. Terbinafine hydrochloride is indicated for interdigital tinea pedis, tinea cruris, and tinea corporis caused by E. floccosum, T. mentagrophytes, and T. rubrum. Similar to miconazole and clotrimazole, terbinafine hydrochloride should be applied sparingly to the affected area twice daily. In clinical trials, this drug demonstrated that it could cure tinea pedis with 1 week of treatment. However, complete resolution of symptoms may require up to 4 weeks of treatment. For athlete’s foot between the toes, patients should apply terbinafine twice a day for 1 week. For athlete’s foot on the bottom or sides of the foot, it should be applied twice a day for 2 weeks. For jock itch and ringworm, patients should apply terbinafine once a day for 1 week or as directed by a primary care provider. 31  BUTENAFINE HYDROCHLORIDE Topical butenafine hydrochloride 1% was reclassified as a nonprescription medication in 2001. Like terbinafine, this antifungal agent is a squalene epoxidase inhibitor. This action results in a deficiency in ergosterol, a corresponding accumulation of squalene within the fungal cell, and eventually cell death. Butenafine hydrochloride is indicated as a cure for tinea pedis between the toes, tinea cruris, and tinea corporis caused by E. floccosum, T. mentagrophytes, and T. rubrum. Similar to other nonprescription topical antifungals, butenafine hydrochloride also relieves the itching, burning, cracking, and scaling that can accompany these conditions. Patients suffering from tinea pedis should be advised to apply a thin film to affected skin between and around toes twice daily for 1 week, once a day for 4 weeks, or as directed by a primary care provider. Patients with tinea cruris or tinea corporis should apply a thin film to the affected area once daily for 2 weeks or as directed by a primary care provider. 32  PRODUCT SELECTION GUIDELINES Cutaneous antifungals are available as ointments, creams, powders, and aerosols. Creams or solutions are the most efficient and effective dosage forms for delivery of the active ingredient to the epidermis. Sprays and powders are less effective because often they are not rubbed into the skin. They are probably more useful as adjuncts to a cream or a solution or as prophylactic agents in preventing new or recurrent infections. 33  PRODUCT SELECTION GUIDELINES Before recommending a nonprescription product, the provider should review the patient’s medical history. For example, patients with diabetes should have their blood glucose levels under control because increased glucose in perspiration may promote fungal growth. Patients with allergic dermatitides often have a history of asthma, hay fever, or atopic dermatitis; therefore, they are extremely sensitive to many oral and topical agents. Acquiring a good medical history may aid in distinguishing a tinea infection from atopic dermatitis and may avoid the recommendation of a product that might cause further skin irritation. 34  COMPLEMENTARY THERAPIES Oil of Bitter Orange, Tea Tree Oil, and Garlic have been used with some success in the management of fungal skin infections, with few or no side effects. 35  NONDRUG MEASURES ▪ To prevent spreading the infection to other parts of the body, either use a separate towel to dry the affected area or dry the affected area last. ▪ Do not share towels, clothing, or other personal articles with household members, especially when an infection is present. ▪ Launder contaminated towels and clothing in hot water, and dry them on a hot dryer setting to prevent spreading the infection. ▪ Cleanse skin daily with soap and water, and thoroughly pat dry to remove oils and other substances that promote growth of fungi. ▪ If possible, do not wear clothing or shoes that cause the skin to stay wet. Wool and synthetic fabrics prevent optimal air circulation. 36  NONDRUG MEASURES ▪ If needed, allow shoes to dry thoroughly before wearing them again. Dust shoes with medicated or non-medicated foot powder to help keep them dry. ▪ If needed, place odor-controlling insoles in casual or athletic shoes. These insoles also provide some support and cushioning for the feet. Change insoles routinely every 3-4 months or more often if their condition warrants. Take care that the shoe fit is not compromised by the insoles. ▪ As with all topical medications, discontinue the use of an antifungal if irritation, sensitization, or worsening of the skin condition occurs. ▪ Avoid contact with people who have fungal infections. Wear protective footwear (e.g., rubber or wooden sandals) in areas of family or public use, such as home bathrooms or community showers. 37  KEY POINTS FOR FUNGAL SKIN INFECTIONS Tinea corporis, tinea cruris, and tinea pedis can be treated with nonprescription drugs. Clotrimazole, miconazole nitrate, terbinafine hydrochloride, butenafine hydrochloride, tolnaftate, and undecylenic acid and its derivatives are efficacious for this purpose. These drugs are effective in all their delivery vehicles, but the powder forms should be reserved only for extremely mild conditions or as adjunctive therapy. Because solutions and creams can spread beyond the affected area, they should be used sparingly. When recommended for suspected or actual dermatophytosis, these topical antifungals should be used twice daily (morning and night). Treatment should be continued for 2-4 weeks, depending on the symptoms. After that time, the patient and/or provider should evaluate the effectiveness of the therapy. To minimize nonadherence, the provider should advise patients that alleviation of symptoms will not occur overnight. Patients should also be cautioned that frequent recurrence of any of these problems is an indication that they should consult a primary care provider. Immunocompromised patients and those with diabetes or circulatory problems should be treated by a primary care provider. 38 THANK YOU! 39