Oral treatments for fungal infections of the skin of the foot

Expert Panel Review of Skin and Hair Dermatophytoses in an Era of Antifungal Resistance

Dermatophytoses are fungal infections of the skin, hair, and nails that affect approximately 25% of the global population. Occlusive clothing, living in a hot humid environment, poor hygiene, proximity to animals, and crowded living conditions are important risk factors. Dermatophyte infections are named for the anatomic area they infect, and include tinea corporis, cruris, capitis, barbae, faciei, pedis, and manuum. Tinea incognito describes steroid-modified tinea. In some patients, especially those who are immunosuppressed or who have a history of corticosteroid use, dermatophyte infections may spread to involve extensive skin areas, and, in rare cases, may extend to the dermis and hair follicle. Over the past decade, dermatophytoses cases not responding to standard of care therapy have been increasingly reported. These cases are especially prevalent in the Indian subcontinent, and Trichophyton indotineae has been identified as the causative species, generating concern regarding resistance to available antifungal therapies. Antifungal-resistant dermatophyte infections have been recently recognized in the United States. Antifungal resistance is now a global health concern. When feasible, mycological confirmation before starting treatment is considered best practice. To curb antifungal-resistant infections, it is necessary for physicians to maintain a high index of suspicion for resistant dermatophyte infections coupled with antifungal stewardship efforts. Furthermore, by forging partnerships with federal agencies, state and local public health agencies, professional societies, and academic institutions, dermatologists can lead efforts to prevent the spread of antifungal-resistant dermatophytes.

Consensus for the Treatment of Tinea Pedis: A Systematic Review of Randomised Controlled Trials

Objective: To systematically review literature enabling the comparison of the efficacy of pharmaceutical treatments for tinea pedis in adults. Design: Systematic review of randomised controlled trials (RCTs) with mycological cure as the primary outcome. Secondary outcomes did include the clinical assessment of resolving infection or symptoms, duration of treatment, adverse events, adherence, and recurrence. Eligibility Criteria: Study participants suffering from only tinea pedis that were treated with a pharmaceutical treatment. The study must have been conducted using an RCT study design and recording age of the participant > 16 years of age. Results: A total of seven studies met the inclusion criteria, involving 1042 participants. The likelihood of resolution in study participants treated with terbinafine was RR 3.9 (95% CI: 2.0−7.8) times those with a placebo. Similarly, the allylamine butenafine was effective by RR 5.3 (95% CI: 1.4−19.6) compared to a placebo. Butenafine was similarly efficacious to terbinafine RR 1.3 (95% CI: 0.4−4.4). Terbinafine was marginally more efficacious than itraconazole, RR 1.3 (95% CI: 1.1−1.5). Summary/Conclusion: Topical terbinafine and butenafine treatments of tinea pedis were more efficacious than placebo. Tableted terbinafine and itraconazole administered orally were efficacious in the drug treatment of tinea pedis fungal infection. We are concerned about how few studies were available that reported the baseline characteristics for each treatment arm and that did not suffer greater than 20% loss to follow-up. We would like to see improved reporting of clinical trials in academic literature. Registration name: Treatment’s for athlete’s foot—systematic review with meta-analysis [CRD42020162078].

Anti-inflammatory effect of lanoconazole on 12-O-tetradecanoylphorbol-13-acetate- and 2,4,6-trinitrophenyl chloride-induced skin inflammation in mice

Background

Lanoconazole (LCZ) is a topical antifungal agent clinically used to treat fungal infections such as tinea pedis. LCZ has not only antifungal effects but also anti‐inflammatory effects, which have the potential to provide additional clinical benefits. However, the characteristic features of the inhibitory effects of LCZ on skin inflammation remain unclear.

Objective

We evaluated the inhibitory effects of topical application of LCZ, and compared the effects of LCZ with those of other antifungal agents including liranaftate, terbinafine and amorolfine.

Methods

Each antifungal agent was topically applied on 12‐O‐tetradecanoylphorbol‐13‐acetate‐induced irritant dermatitis and 2,4,6‐trinitrophenyl chloride‐induced contact dermatitis in mice (BALB/c). The ear thickness, myeloperoxidase activity and inflammatory mediator contents were evaluated.

Results

LCZ dose‐dependently suppressed 12‐O‐tetradecanoylphorbol‐13‐acetate‐induced irritant dermatitis, suppressed the production of neutrophil chemotactic factors such as keratinocyte‐derived chemokine and macrophage inflammatory protein‐2, and inhibited neutrophil infiltration to the inflammation site. Moreover, 1% LCZ reduced the ear swelling in mice with 2,4,6‐trinitrophenyl chloride‐induced contact dermatitis in accordance with the inhibition of interferon‐γ production. The inhibitory potency of LCZ on these types of dermatitis in mice was stronger than that of other types of antifungal agents.

Conclusion

The anti‐inflammatory effects of LCZ were exerted through the inhibition of inflammatory mediator production. These effects may contribute to the relief of dermatitis symptoms in patients with tinea pedis.

Topical antifungal treatments for tinea cruris and tinea corporis

BACKGROUND

Tinea infections are fungal infections of the skin caused by dermatophytes. It is estimated that 10% to 20% of the world population is affected by fungal skin infections. Sites of infection vary according to geographical location, the organism involved, and environmental and cultural differences. Both tinea corporis, also referred to as 'ringworm' and tinea cruris or 'jock itch' are conditions frequently seen by primary care doctors and dermatologists. The diagnosis can be made on clinical appearance and can be confirmed by microscopy or culture. A wide range of topical antifungal drugs are used to treat these superficial dermatomycoses, but it is unclear which are the most effective.

OBJECTIVES

To assess the effects of topical antifungal treatments in tinea cruris and tinea corporis.

SEARCH METHODS

We searched the following databases up to 13th August 2013: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2013, Issue 7), MEDLINE (from 1946), EMBASE (from 1974), and LILACS (from 1982). We also searched five trials registers, and checked the reference lists of included and excluded studies for further references to relevant randomised controlled trials. We handsearched the journal Mycoses from 1957 to 1990.

SELECTION CRITERIA

Randomised controlled trials in people with proven dermatophyte infection of the body (tinea corporis) or groin (tinea cruris).

DATA COLLECTION AND ANALYSIS

Two review authors independently carried out study selection, data extraction, assessment of risk of bias, and analyses.

MAIN RESULTS

Of the 364 records identified, 129 studies with 18,086 participants met the inclusion criteria. Half of the studies were judged at high risk of bias with the remainder judged at unclear risk. A wide range of different comparisons were evaluated across the 129 studies, 92 in total, with azoles accounting for the majority of the interventions. Treatment duration varied from one week to two months, but in most studies this was two to four weeks. The length of follow-up varied from one week to six months. Sixty-three studies contained no usable or retrievable data mainly due to the lack of separate data for different tinea infections. Mycological and clinical cure were assessed in the majority of studies, along with adverse effects. Less than half of the studies assessed disease relapse, and hardly any of them assessed duration until clinical cure, or participant-judged cure. The quality of the body of evidence was rated as low to very low for the different outcomes.Data for several outcomes for two individual treatments were pooled. Across five studies, significantly higher clinical cure rates were seen in participants treated with terbinafine compared to placebo (risk ratio (RR) 4.51, 95% confidence interval (CI) 3.10 to 6.56, number needed to treat (NNT) 3, 95% CI 2 to 4). The quality of evidence for this outcome was rated as low. Data for mycological cure for terbinafine could not be pooled due to substantial heterogeneity.Mycological cure rates favoured naftifine 1% compared to placebo across three studies (RR 2.38, 95% CI 1.80 to 3.14, NNT 3, 95% CI 2 to 4) with the quality of evidence rated as low. In one study, naftifine 1% was more effective than placebo in achieving clinical cure (RR 2.42, 95% CI 1.41 to 4.16, NNT 3, 95% CI 2 to 5) with the quality of evidence rated as low.Across two studies, mycological cure rates favoured clotrimazole 1% compared to placebo (RR 2.87, 95% CI 2.28 to 3.62, NNT 2, 95% CI 2 to 3).Data for several outcomes were pooled for three comparisons between different classes of treatment. There was no difference in mycological cure between azoles and benzylamines (RR 1.01, 95% CI 0.94 to 1.07). The quality of the evidence was rated as low for this comparison. Substantial heterogeneity precluded the pooling of data for mycological and clinical cure when comparing azoles and allylamines. Azoles were slightly less effective in achieving clinical cure compared to azole and steroid combination creams immediately at the end of treatment (RR 0.67, 95% CI 0.53 to 0.84, NNT 6, 95% CI 5 to 13), but there was no difference in mycological cure rate (RR 0.99, 95% CI 0.93 to 1.05). The quality of evidence for these two outcomes was rated as low for mycological cure and very low for clinical cure.All of the treatments that were examined appeared to be effective, but most comparisons were evaluated in single studies. There was no evidence for a difference in cure rates between tinea cruris and tinea corporis. Adverse effects were minimal - mainly irritation and burning; results were generally imprecise between active interventions and placebo, and between different classes of treatment.

AUTHORS' CONCLUSIONS

The pooled data suggest that the individual treatments terbinafine and naftifine are effective. Adverse effects were generally mild and reported infrequently. A substantial number of the studies were more than 20 years old and of unclear or high risk of bias; there is however, some evidence that other topical antifungal treatments also provide similar clinical and mycological cure rates, particularly azoles although most were evaluated in single studies.There is insufficient evidence to determine if Whitfield's ointment, a widely used agent is effective.Although combinations of topical steroids and antifungals are not currently recommended in any clinical guidelines, relevant studies included in this review reported higher clinical cure rates with similar mycological cure rates at the end of treatment, but the quality of evidence for these outcomes was rated very low due to imprecision, indirectness and risk of bias. There was insufficient evidence to confidently assess relapse rates in the individual or combination treatments.Although there was little difference between different classes of treatment in achieving cure, some interventions may be more appealing as they require fewer applications and a shorter duration of treatment. Further, high quality, adequately powered trials focusing on patient-centred outcomes, such as patient satisfaction with treatment should be considered.

Nail and skin disorders of the foot

Disorders of the dermis and the nails on the feet are common. Despite the simplicity of the skin and nail disorders of the foot, they can be debilitating and impact the patient's ability to ambulate and perform activities of daily living. Diagnosis in most cases is confirmed on physical examination alone. Diligent care of skin and nail disorders can prevent further pathology involving the deeper structures of the foot and allow the patient to fully participate in their usual activities.

A pragmatic strategy for the review of clinical evidence

BACKGROUND

Systematic reviews (SR) of clinical evidence are rightfully considered the basis for developing recommendations to support decisions in current practice. To avoid bias, SRs are expected to be systematic in their research strategy and are exhaustive. The drawback of the latter criteria relies in the substantial work needed to conduct and keep SRs updated. The objective of this paper is to compare a research strategy based on the review of a selected number of core journals, which we consider a 'pragmatic review' (PR), with that derived by an SR in estimating the efficacy of treatments.

METHODS

Five clinical areas were considered for the comparison between the two strategies: chronic obstructive pulmonary disease, dermatology, heart failure, renal diseases and stroke. We extracted a systematic sample from all the Cochrane SRs pertaining to each area and were published before April 2010. Two groups of journals were considered in the PR: six general journals that commonly published research for the five clinical areas, and five specialist journals with the highest impact factor in each area. To assess the agreement in the findings of SRs and PRs, we considered both the direction of the estimates and P-values.

RESULTS

A sample of 27 SRs included 171 overall analyses and 259 subgroup analyses related to primary outcomes. The PR captured one or more clinical trials in 24 of the 27 SRs (89%), and 118 of the 171 overall analyses (69%) were replicated. The PR supported the recommendations to use (or not) the study treatment in 11 of the 13 SRs (85%), which ended with a clinical recommendation.

CONCLUSIONS

We verified in a sample of SRs that the conclusion of a research strategy based on a pre-defined set of general and specialist medical journals is able to replicate almost all the clinical recommendations of a formal SR.

A study to evaluate the price control of antifungal medicines and its practical applicability

Background:

Superficial fungal infections are common and treatment imposes economic burden on the patients. Government of India had introduced price control over griseofulvin and tolnaftate in 1995; however, this measure can only benefit the needy if the policy is harmonized with the health-care service provider, that is, dermatologists. The aim of this study was to evaluate the existing Government mechanisms over price control of antifungal medications and its reach to the people-in-need.

Materials and Methods:

A questionnaire-based, cross-sectional study was carried out over a period of 6 months. Questionnaire was mailed to members of a state branch of Indian Association of Dermatologists, Venereologists, and Leprologists. Responses reaching investigators within 2 months from the date of mailing were finally analyzed.

Results:

Among 93 (41.33%) respondents, only 6 (6.5%) were aware of existing price control over griseofulvin but none about tolnaftate. Thirty-nine (41.9%) respondents were in favor of introducing price control on terbinafine and 42 (45.2%) for itraconazole. The topically preferred antifungals were primarily azoles and terbinafine, while among systemic antifungals, dermatologists mostly preferred fluconazole and terbinafine. The choice of antifungals by the dermatologists matched with the evidence-based dermatology data.

Conclusion:

Currently, price-controlled antifungal drugs are less commonly used by practitioners. Although the dermatologists favor price control, the initiative undertaken by the Government has not reached them. This shows the need to bridge the gap between policy makers and health-care service providers to help the ailing population.

Oral treatments for fungal infections of the skin of the foot

BACKGROUND

About 15% of the world population have fungal infections of the feet (tinea pedis or athlete's foot). There are many clinical presentations of tinea pedis, and most commonly, tinea pedis is seen between the toes (interdigital) and on the soles, heels, and sides of the foot (plantar). Plantar tinea pedis is known as moccasin foot. Once acquired, the infection can spread to other sites including the nails, which can be a source of re-infection. Oral therapy is usually used for chronic conditions or when topical treatment has failed.

OBJECTIVES

To assess the effects of oral treatments for fungal infections of the skin of the foot (tinea pedis).

SEARCH METHODS

For this update we searched the following databases to July 2012: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library, MEDLINE (from 1946), EMBASE (from 1974), and CINAHL (from 1981). We checked the bibliographies of retrieved trials for further references to relevant trials, and we searched online trials registers.

SELECTION CRITERIA

Randomised controlled trials of oral treatments in participants who have a clinically diagnosed tinea pedis, confirmed by microscopy and growth of dermatophytes (fungi) in culture.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook study selection, 'Risk of bias' assessment, and data extraction.

MAIN RESULTS

We included 15 trials, involving 1438 participants. The 2 trials (71 participants) comparing terbinafine and griseofulvin produced a pooled risk ratio (RR) of 2.26 (95% confidence interval (CI) 1.49 to 3.44) in favour of terbinafine's ability to cure infection. No significant difference was detected between terbinafine and itraconazole, fluconazole and itraconazole, fluconazole and ketoconazole, or between griseofulvin and ketoconazole, although the trials were generally small. Two trials showed that terbinafine and itraconazole were effective compared with placebo: terbinafine (31 participants, RR 24.54, 95% CI 1.57 to 384.32) and itraconazole (72 participants, RR 6.67, 95% CI 2.17 to 20.48). All drugs reported adverse effects, with gastrointestinal effects most commonly reported. Ten of the trials were published over 15 years ago, and this is reflected by the poor reporting of information from which to make a clear 'Risk of bias' assessment. Only one trial was at low risk of bias overall. The majority of the remaining trials were judged as 'unclear' risk of bias because of the lack of clear statements with respect to methods of generating the randomisation sequence and allocation concealment. More trials achieved blinding of participants and personnel than blinding of the outcome assessors, which was again poorly reported.

AUTHORS' CONCLUSIONS

The evidence suggests that terbinafine is more effective than griseofulvin, and terbinafine and itraconazole are more effective than no treatment. In order to produce more reliable data, a rigorous evaluation of different drug therapies needs to be undertaken with larger sample sizes to ensure they are large enough to show any real difference when two treatments are being compared. It is also important to continue to follow up and collect data, preferably for six months after the end of the intervention period, to establish whether or not the infection recurred.

Comparison of the in vitro activity of terbinafine and lanoconazole against dermatophytes

The objective of this study was to compare the antifungal activity of terbinafine (TERB) with that of lanoconazole (LAN). Test isolates, which were clinical isolates of Japanese origin, included 10 strains each of Trichophyton rubrum, T. mentagrophytes and Epidermophyton floccosum. The minimum inhibitory concentration (MIC) of TERB and LAN against each dermatophyte isolate was determined according to the Clinical and Laboratory Standards Institute microbroth methodology, M38-A2. Minimum fungicidal concentrations were determined by subculturing the contents of each visibly clear well from the MIC assay for colony count. All LAN MICs were <or=0.008 microg ml(-1), while the TERB range was 0.008-0.03 microg ml(-1). Moreover, by standard definition, LAN was fungistatic against most strains, whereas TERB was fungicidal. Both LAN and TERB demonstrated potent antifungal activity against dermatophytes; however, the lack of fungicidal activity by LAN needs to be evaluated in terms of potential clinical efficacy.

Reported incidence and treatment of dermatophytosis in children in general practice: a comparison between 1987 and 2001

INTRODUCTION

Dermatophytosis is a common skin infection in children. Although the epidemiology is relatively unknown it is becoming a major health problem in some countries. We determine the incidence and management of dermatophytosis in Dutch general practice in 1987 and 2001.

METHODS

We used data of all children aged 0-17 years derived from two national surveys performed in Dutch general practice in 1987 and 2001 respectively. All diagnoses, prescriptions and referrals were registered over a 12 months period by the participating general practitioners (GPs), 161 and 195 respectively. Data were stratified for socio-demographic characteristics.

RESULTS

Compared to 1987, in 2001 the total reported incidence rate of dermatophytosis in children in general practice increased from 20.8 [95%CI 18.9-22.8] to 24.6 [95%CI 23.5-25.7] per 1,000 person years. Infants (<1 year), girls, children in rural areas and children of non-western immigrants more often consulted the GP for dermatophytosis in 2001. In both surveys GPs treated the majority of children with dermatophytosis with topical drugs, especially with azoles.

CONCLUSIONS

The reported incidence rate of dermatophytosis in children in general practice increased; however it is unclear whether this is a consequence of an increasing prevalence in the population or a changing help seeking behaviour. GPs generally follow the national guideline for the treatment of dermatophytosis in children.

The safety of oral antifungal treatments for superficial dermatophytosis and onychomycosis: a meta-analysis

PURPOSE

We estimated the absolute risks of treatment termination and incidence of adverse liver outcomes among all commonly used oral antifungal treatments for superficial dermatophytosis and onychomycosis.

METHODS

MEDLINE, EMBASE, and Cochrane Library were searched to identify randomized and nonrandomized controlled trials, case series, and cohort studies published before December 31, 2005. Two reviewers independently applied selection criteria, performed quality assessment, and extracted data. Treatment arms with the same regimen in terms of drug, type (continuous or intermittent), and dosage were combined to estimate the risk of an outcome of interest.

RESULTS

We identified 122 studies with approximately 20,000 enrolled patients for planned comparison. The pooled risks (95% confidence intervals) of treatment discontinuation resulting from adverse reactions for continuous therapy were 3.44% (95% confidence interval [CI], 2.28%-4.61%) for terbinafine 250 mg/day; 1.96% (95% CI, 0.35%-3.57%) for itraconazole 100 mg/day; 4.21% (95% CI, 2.33%-6.09%) for itraconazole 200 mg/day; and 1.51% (95% CI, 0%-4.01%) for fluconazole 50 mg/day. For intermittent therapy, the pooled risks were as follows: pulse terbinafine: 2.09% (95% CI, 0%-4.42%); pulse itraconazole: 2.58% (95% CI, 1.15%-4.01%); intermittent fluconazole 150 mg/week: 1.98% (95% CI, 0.05%-3.92%); and intermittent fluconazole 300 to 450 mg/week: 5.76% (95% CI, 2.42%-9.10%). The risk of liver injury requiring termination of treatment ranged from 0.11% (continuous itraconazole 100 mg/day) to 1.22% (continuous fluconazole 50 mg/day). The risk of having asymptomatic elevation of serum transaminase but not requiring treatment discontinuation was less than 2.0% for all treatment regimens evaluated.

CONCLUSION

Oral antifungal therapy against superficial dermatophytosis and onychomycosis, including intermittent and continuous terbinafine, itraconazole, and fluconazole, was associated with a low incidence of adverse events in an immunocompetent population.

Errors in search strategies were identified by type and frequency

OBJECTIVE

Errors in the electronic search strategy of a systematic review may undermine the integrity of the evidence base used in the review. We studied the frequency and types of errors in reviews published by the Cochrane Collaboration.

STUDY DESIGN AND SETTING

Data sources were MEDLINE searches from reviews in the Cochrane Library, Issue 3, 2002. To be eligible, systematic reviews must have been of randomized or quasi-randomized controlled trials, reported included and excluded studies, and used one or more sections of the Cochrane Collaboration's Highly Sensitive Search Strategy. MEDLINE search strategies not reported in enough detail to be assessed or that were duplicates of a search strategy already assessed for the study were excluded. Two librarians assessed eligibility and scored the eligible electronic search strategies for 11 possible errors. Dual review with consensus was used.

RESULTS

Of 105 MEDLINE search strategies examined, 63 were assessed; 31 were excluded because they were inadequately reported, and 11 were duplicates of assessed search strategies. Most (90.5%) of the assessed search strategies contained > or =1 errors (median 2, interquartile range [IQR] 1.0-3.0). Errors that could potentially lower recall of relevant studies were found in 82.5% (median 1, IQR 1.0-2.0) and inconsequential errors (to the evidence base) were found in 60.3% (median 1, IQR 0.0-1.0) of the search strategies. The most common search errors were missed MeSH terms (44.4%), unwarranted explosion of MeSH terms (38.1%), and irrelevant MeSH or free text terms (28.6%). Missed spelling variants, combining MeSH and free text terms in the same line, and failure to tailor the search strategy for other databases occurred with equal frequency (20.6%). Logical operator error occurred in 19.0% of searches.

CONCLUSION

When the MEDLINE search strategy used in a systematic review is reported in enough detail to allow assessment, errors are commonly revealed. Additional peer review steps are needed to ensure search quality and freedom from errors.

What defines the quality of patient care in tinea pedis?

OBJECTIVES

The aim of this study has been to evaluate patients with tinea pedis for their demographic data and attitudes affecting the treatment of disease, and to compare the in vitro activity of 10 antifungal agents and to relate them to their in vivo activity.

METHODS

Patients with positive mycological examination were enrolled in the study, and a questionnaire comprised of 22 questions was administered. A mycological culture was carried out for each specimen. The antifungal susceptibility of the subcultured species was determined for griseofulvin, terbinafine, ciclopiroxolamine, fluconazole, ketoconazole, itraconazole, bifonazole, sulconazole, oxiconazole and miconazole with microdilution.

RESULTS

Mycological cultures were carried out from 59 patients and there were 35 positive cultures (59.3%). The dermatophytes were Trichophyton rubrum (n = 25) and Trichophyton mentagrophytes (n = 3). The yeasts were Candida albicans (n = 7), Candida glabrata (n = 1) and Trichosporon (n = 2). In the minimum inhibitory concentration (MIC) study, the mean +/- standard error of the mean (SEM) MICs of the antifungals for T. rubrum were as follows: terbinafine 0.01 +/- 0.003, oxiconazole 0.16 +/- 0.05, sulkonazole 0.31 +/- 0.05, miconazole 0.45 +/- 0.15, itraconazole 0.74 +/- 0.01, ketokonazole 1.03 +/- 0.17, ciclopiroxolamine 1.30 +/- 0.12, bifonazole 1.94 +/- 0.51, griseofulvin 4.87 +/- 0.61, and fluconazole 17.91 +/- 3.67 microg/mL.

CONCLUSION

Our study supports that azoles could be used as first-line treatment, as oxiconazole is very effective for both dermatophytes and C. albicans. Correlation between in vitro results and clinical outcomes of cases of dermatophytes is still to be established and interpretive breakpoints defined, in order to increase the quality of patient care in tinea pedis.

Dermatology for the practicing allergist: Tinea pedis and its complications

Tinea pedis is a chronic fungal infection of the feet, very often observed in patients who are immuno-suppressed or have diabetes mellitus. The practicing allergist may be called upon to treat this disease for various reasons. Sometimes tinea infection may be mistaken for atopic dermatitis or allergic eczema. In other patients, tinea pedis may complicate allergy and asthma and may contribute to refractory atopic disease. Patients with recurrent cellulitis may be referred to the allergist/immunologist for an immune evaluation and discovered to have tinea pedis as a predisposing factor. From a molecular standpoint, superficial fungal infections may induce a type2 T helper cell response (Th2) that can aggravate atopy. Th2 cytokines may induce eosinophil recruitment and immunoglobulin E (IgE) class switching by B cells, thereby leading to exacerbation of atopic conditions. Three groups of fungal pathogens, referred to as dermatophytes, have been shown to cause tinea pedis: Trychophyton sp, Epidermophyton sp, and Microsporum sp. The disease manifests as a pruritic, erythematous, scaly eruption on the foot and depending on its location, three variants have been described: interdigital type, moccasin type, and vesiculobullous type. Tinea pedis may be associated with recurrent cellulitis, as the fungal pathogens provide a portal for bacterial invasion of subcutaneous tissues. In some cases of refractory asthma, treatment of the associated tinea pedis infection may induce remission in airway disease. Very often, protracted topical and/or oral antifungal agents are required to treat this often frustrating and morbid disease. An evaluation for underlying immuno-suppression or diabetes may be indicated in patients with refractory disease.

Skin infections and ageing

Elderly individuals have an increased susceptibility to skin infections due to age-related anatomical, physiological and environmental factors. The types of organisms that cause primary skin and soft tissue infections are diverse, and include bacterial, viral and fungal pathogens as well as parasites. In the elderly, these infections and infestations may present with atypical signs and symptoms or may complicate underlying chronic skin disorders. Clinical features, investigations and management of the following important and common skin infections are described in more detail: cellulitis, erysipelas, necrotizing fasciitis, impetigo, folliculitis, furunculosis and carbunculosis, erythrasma, herpes zoster and postherpetic neuralgia, herpes simplex, warts, molluscum contagiosum, dermatophytosis of the skin, hair and nails, candidiasis, and scabies. Treatment should be based on the results of the appropriate diagnostic tests. Correct diagnosis and therapy of skin infections lead to satisfactory outcome in the majority of elderly patients.