Tinea pedis is a common and frequent disease in dermatology, which has a great impact on patients’ health and quality of life, and unreasonable and unregulated diagnosis and treatment often lead to a low cure rate and a high recurrence rate. In order to standardize the diagnosis and treatment of tinea pedis, some experts from the Dermatology Branch of the Chinese Medical Association have developed this guideline on the basis of evidence-based medicine, and its content will be revised continuously as the discipline develops to meet the needs of Chinese dermatologists.
1. Definition
Tinea pedis is a fungal infection of the foot caused by dermatophytes that primarily involves the interdigital, plantar, and lateral margins of the foot. Dermatophytosis that infects only the dorsum of the foot is called tinea corporis. Infections caused by non-dermatophyte fungi such as Candida can also be seen on the foot, which should be called dermatophytic candidiasis of the foot at this time.
2.Pathogenic bacteria
The causative organisms of tinea pedis are dermatophytes, including the genera Microsporum, Trichophyton and Tinea epidermidis. More than 80% of them are Trichophyton rubrum, followed by Trichophyton rubrum and Trichophyton flocculare. Superficial fungal infections of the foot can also be caused by non-dermatophytes (such as Candida, etc.), but they are not included in this consensus discussion.
3. Epidemiology
Tinea pedis is the most prevalent dermatophyte fungal disease, with an incidence of about 15% or as high as 30% to 70% in the population, and has been reported to account for about 10% to 20% of patients seen in dermatology clinics in China. Epidemiological data in China show that the causative agent of tinea pedis is mainly Trichophyton rubrum, followed by Trichophyton rubrum, Trichophyton discontinua, and Trichophyton flocculare. The onset of tinea pedis is related to environmental and seasonal factors, and it is especially common in hot and humid areas and high-temperature seasons; it is also related to specific groups of people or occupations, including athletes, coal miners, soldiers, diabetics, and AIDS patients, and is associated with factors such as sweaty feet, tight footwear, or impaired immunity; tinea pedis is familial and contagious and can be spread by contact with items used by patients in public places such as swimming pools, baths, or at home. It can be spread by contact with objects used by patients in public places such as swimming pools and baths or at home; also, the patients themselves can spread between different anatomical sites, for example, tinea pedis can cause tinea nail, tinea cruris, tinea corporis, etc. The recurrence rate of tinea pedis is high, with about 84% of patients having more than two attacks per year on average. Tinea pedis has a significant impact on patients’ health and quality of life surveys show that tinea pedis has a significant impact on patients’ work, social life and daily life with ratios as high as 80% and 75%; more than half of patients have sleep disruption due to itching and up to 40% of patients have complications with bacterial infections.
4.Clinical manifestations
The most common clinical symptoms of tinea pedis are pruritus (96.9%), desquamation (72.8%), and blistering (55.7%), which are divided into blistering type, interdigital erosion type, and scaly keratosis type according to the morphology of lesions; and interdigital, plantar, and mixed types according to the site of infection, with interdigital type being the most common.
4.1 Blister type
In between the toes and the soles of the feet can be seen pinhead to corn size deep in the blisters, blister wall is thick, scattered or dense distribution, can be honeycomb fusion, can also be seen large blisters. This type is prone to secondary bacterial infections and ringworm rash. The causative agent is mostly Trichophyton rubrum.
4.2 Interdigital eruption
It is most common between the 4th and 5th toes. The rash is initially macerated, often caused by itching and rubbing to break the epidermis, erosion, may be accompanied by oozing, often emitting an unpleasant odor. It is susceptible to secondary bacterial infections, which can lead to dermatitis or cellulitis. The causative agents are often Trichophyton rubrum, Trichophyton spp. and Trichophyton flocculare.
4.3 Scaly keratinized type
It is quite common and invades the soles, lateral edges and heels of the feet. The lesions appear as thickened, flaky, rough skin and are prone to cracking in winter. Many cases of lichen planus are combined with tinea pedis, often involving one hand and presenting a special/bipedal hand. The causative organism is mainly Trichophyton rubrum.
5.Fungal examination
This includes fungal microscopy and culture, both of which should be done whenever possible. The material should be scraped from the scales or blister wall at the edge of the lesion, and the amount of specimen should be sufficient. Under the microscope to see mycelium or arthrospores is positive. Fungal culture and strain identification can clarify the causative organism.
6.Diagnosis and differential diagnosis
Tinea pedis can be diagnosed based on typical clinical manifestations and positive mycological examination. Since the results of mycological examination are influenced by many factors, even if the results are negative, fungal infection cannot be completely excluded and should be judged in combination with clinical aspects. Tinea pedis needs to be differentiated from the following diseases: e.g., sweat rash, palmoplantar pustulosis, eczema, contact dermatitis, exfoliative keratosis, palmoplantar keratosis, and continuous acrodermatitis, and also from other microbial infections (e.g., candidiasis, pustular bacterial rash, and stage II syphilis).
7.Treatment goal of tinea pedis
is to remove pathogenic bacteria, quickly relieve symptoms and prevent recurrence. There are three main methods of treatment, namely, local treatment, systemic treatment, and combined treatment of both. Different treatment methods should be chosen according to the type of pathogenic bacteria, clinical typing and the basic condition of the patient. At present, antifungal drugs commonly used in the treatment of tinea pedis include: azoles, arylamides, thioureas, morpholines, pyrones, etc. Among them, acrylamides and azoles are most widely used clinically.
7.1 Topical treatment
Topical treatment has the advantages of rapid onset of action, high safety and low cost, and is usually widely used. Drug formulations include creams, solutions, gels, sprays and powders, etc. The appropriate dosage form should be selected according to the characteristics of the lesions. Commonly used azoles include miconazole, econazole, clotrimazole, ketoconazole and bifenazole, which are used once or twice daily for at least 4 weeks and have a fungal cure rate of 60% to 91%; arylamines include terbinafine, butenafine and naftifine, which are used once or twice daily for at least 2 weeks and have a fungal cure rate of 62% to 100%. Other topical medications used to treat tinea pedis include morpholinoids (e.g., amorolfine), pyrrolidones (e.g., ciclopirox), and thioureas (e.g., rilaparatide). In addition, some keratin exfoliating agents also have some antifungal effect, such as salicylic acid, levulinic acid, etc. Certain herbal preparations such as tincture of hygrophil are also used clinically. Although topical medications are commonly used as a treatment method, there are certain limitations, such as poor patient compliance, as data show that 82.5% of patients with tinea pedis use topical medications for less than 2 weeks; uneven application of medications can easily cause skin lesions to be missed, which can also cause physical and psychological discomfort to patients; and poor penetration of medications for scaly keratinized tinea pedis. The above reasons often lead to poor efficacy and high recurrence rate (50%~80%) of topical treatment alone. Therefore, this consensus suggests that topical treatment alone should only be used for patients with initial or limited lesions of tinea pedis.
7.2 Systemic treatment
Oral antifungal drugs can effectively treat tinea pedis, with the advantages of short course, convenient administration, no missed lesions, high patient compliance, and low recurrence rate. It is suitable for those who have poor results of local treatment, recurrent attacks, scaly keratinized type, large area of involvement, with certain systemic diseases (such as diabetes, AIDS, etc.) and those who do not want to receive local treatment. Studies have shown that oral terbinafine 250/d for 1-2 weeks for tinea pedis has a fungal cure rate of 89.3% at 12 weeks, with an annual recurrence rate of only about 10% at 3 years of follow-up; oral terbinafine for 1 week has similar efficacy and safety to topical clotrimazole cream for 4 weeks. Itraconazole 400/d shock treatment for 1 week was also effective, with a fungological efficiency of 56%, but studies of long-term efficacy were lacking. There is less information on the treatment of tinea pedis with fluconazole. The safety of terbinafine and itraconazole has been confirmed by numerous clinical studies at home and abroad, but they should be used with reference to the instructions for certain special populations.
7.3 Combination of topical drugs plus oral drugs
Because of the limitations of both topical and systemic treatments, the combination of topical antifungal drugs plus oral antifungal drugs is increasingly being promoted in clinical practice. A single-center randomized controlled open study in China showed that the combination of oral terbinafine 250/d for 1 week and topical terbinafine cream for 1 week (referred to as the “1+1” combination regimen) was as effective and safe as the oral terbinafine 250/d for 2 weeks group, but had a faster onset of action than the latter, and its The efficacy was significantly better than that of the 2-week topical terbinafine group and the 4-week bifenoconazole group. The study showed that the combination regimen (“1+1”) showed advantages in shortening the treatment course, reducing costs, improving compliance and efficacy, and reducing the recurrence rate. It is especially suitable for those with recurrent attacks and poor compliance. When tinea pedis is combined with bacterial infection, antibacterial treatment should be given first, and local lesions should be treated according to the principles of eczema treatment, followed by antifungal treatment after the bacterial infection is controlled. If the pathogenic bacteria is clearly Candida infection, azole drugs should be preferred for treatment.
8. Prevention
Tinea pedis can be cured, but it is prone to recurrence or reinfection. Good health education is essential to prevent tinea pedis, reduce recurrence, and reduce transmission. Pay attention to personal hygiene, such as using your own slippers and bath towels. Keep your feet dry and wear breathable shoes and socks. Pay attention to public hygiene. Actively treat ringworm, and you need to treat ringworm in other parts of yourself (especially nail fungus), as well as in family members and pets at the same time.
In summary, the diagnosis and treatment consensus for tinea pedis is as follows.
①The causative organism of tinea pedis is dermatophytes.
②The diagnosis of tinea pedis should be based on clinical manifestations combined with fungal microscopy and fungal culture.
③The goal of tinea pedis treatment is to remove the causative organism, quickly relieve symptoms, and prevent recurrence. Topical therapy, systemic therapy or combination therapy can be used for tinea pedis treatment.
④Topical treatment is suitable for patients with initial or limited lesions of tinea pedis. You can choose acrylamides or azoles as well as other types of topical antifungal drugs, and a full course of medication is required.
⑤ Systemic treatment is indicated for patients with poor results of local treatment, recurrent attacks, scaly keratinized type, large area of involvement, or with certain systemic diseases (such as diabetes, AIDS, etc.) and those who do not want to receive local treatment.
(6) Combined topical and systemic treatment regimens (one topical plus one oral antifungal) have advantages in shortening the course of treatment, reducing costs, improving compliance and efficacy, and reducing the recurrence rate. It is especially suitable for those with recurrent attacks and poor compliance.
(7) In the combined local and systemic treatment regimen, oral drugs are recommended to use terbinafine 250/d for 1-2 weeks; if terbinafine is not effective, azole antifungal drugs can be considered (e.g. itraconazole shock therapy, 200, 2 times/d for 1 week; continuous therapy, 200 mg/d for 2 weeks).
⑧ Topical drugs can be chosen from acrylamides, azoles or other types of antifungal drugs (Table 1).
Table 1 Recommended use regimens by some experts in the treatment of tinea pedis in the Dermatology Branch of the Chinese Medical Association
Treatment regimen First regimen Second regimen
Topical treatment Topical acrylamides for 2-4 weeks (pay attention to the choice of dosage form) Topical azoles and other types of antifungal agents for 4 weeks
Systemic treatment Oral terbinafine 250mg/d for 2 weeks Oral itraconazole 200~400mg/d for 1~2 weeks
Combination therapy Oral terbinafine 250mg/d + topical antifungal drug for 1~2 weeks Oral itraconazole 400mg/d + topical antifungal drug for 1~2 weeks
Note: * Combination therapy is a topical plus an oral antifungal drug