Treatment of onychomycosis in an era of antifungal resistance: Role for antifungal stewardship and topical antifungal agents

[Onychomycosis in children and adolescents-case report and overview of the literature]

Fungal nail infections in children and adolescents are on the rise worldwide. Diagnosis and, above all, treatment is a challenge. A 15-year-old girl had been suffering from onychomycosis of the toenails for more than 6 years, and later also of a fingernail on her right hand. Trichophyton (T.) rubrum had already been identified by culture and polymerase chain reaction (PCR) as the pathogen years ago. However, treatment attempts with topical antimycotics and fluconazole did not lead to a cure. Mycological diagnostics using PCR and sequencing of the ITS (Internal Transcribed Spacer) region of the rDNA of the dermatophyte confirmed the diagnosis of tinea unguium caused by T. rubrum. Ciclopiroxolamine-containing water-soluble nail varnish and oral terbinafine were used for treatment, both in off-label use and with the consent of the girl's parents. Terbinafine was given continuously once daily and subsequently intermittently once weekly. After 7 months of combined antifungal therapy, the nail mycosis of the fingernails and toenails healed completely. The endpoint of the therapy was clinical healing and negative PCR for T. rubrum. There have been no recurrences over the past more than 3 years-first under prophylaxis with the antifungal nail varnish.

Lipid-based nanoformulations in onychomycosis therapy: addressing challenges of current therapies and advancing treatment

Onychomycosis significantly impacts approximately 20% of the global population. The physical barriers of the nail structure make fungal infections a persistent therapeutic challenge. Traditional approaches, including topical and oral antifungal agents, have limitations such as toxicities, low nail permeability, adverse effects, and high recurrence rates. Consequently, emerging lipid-based delivery systems have gained interest because of their potential to address these drawbacks. Nanostructured lipid carriers (NLCs), solid lipid nanoparticles (SLNs), liposomes, and transferosomes are innovative formulations that offer enhanced drug solubility, sustained release, and targeted delivery to the nail matrix. These lipid-mediated approaches have shown promise in overcoming the hurdles associated with conventional therapies, thereby improving treatment outcomes, patient compliance, and the overall quality of life. A comprehensive review focusing on the potential of lipid-based drug delivery systems in treating onychomycosis is lacking in the existing literature. This review explores various aspects of the clinical presentation of onychomycosis, available treatments, challenges associated with treatment, formulation science related to lipid-based vehicles and their applications, highlighted by the promising aspects of these novel formulations, and provides insights into clinical developments. In addition, the regulatory perspective is critical to such development, and approval is discussed, particularly in managing regulatory compliance complexities to ensure successful implementation. The holistic approach provides a comprehensive basis for determining lipid-based drug delivery systems' state-of-the-art and future scope.

Analysis of Causative Factors and Potential Predictors of Onychomycosis: A Retrospective Single-Center Study in Poland

Onychomycosis is a fungal nail infection which has a considerable impact on the quality of life of patients. The aim of this study was to analyze onychomycosis cases with respect to fungal species, infection sites, and patient demographics such as age and sex. Furthermore, we assessed whether simple clinical and demographic data could predict positive results for mycological culture. A retrospective analysis of 2722 patients who had nail samples investigated with direct microscopy and mycological culture was performed. The fungi most frequently identified were Trichophyton rubrum in the toenails and Candida albicans in the fingernails, with a detailed incidence varying by age and sex. Predictive models, including logistic regression and k-nearest neighbors, did not provide clinically useful accuracy. Therefore, it is necessary to perform confirmatory diagnostics before starting antifungal treatment.

Patient Characteristics, Diagnostic Testing Utilization, and Antifungal Prescribing Pattern for Onychomycosis in the USA: A Cohort Study Using DataDerm, 2016-2022

Introduction

Onychomycosis is a complex nail disease that is commonly seen in daily practice.

Methods

Electronic health records of clinically diagnosed onychomycosis patients were extracted using DataDerm - a dermatology data registry hosted by the American Academy of Dermatology - spanning from the year 2016 to 2022.

Results

Regardless of age, an increasing trend in patient volume was observed in the Southern US region, which accounted for 50.7-56.9% of onychomycosis patients in 2022. A coinfection of tinea pedis was present among 15.6-22.5% of patients. Diagnostic testing was infrequently utilized with less than one-quarter of patients having a histopathologic examination (12.7-21.9%) followed by fungal culture (5.5-8.2%) and direct microscopic examination (3.3-6.0%). Treatments were infrequently prescribed, accounting for less than one-quarter of patients (orals, terbinafine: 20.8-29.1%, fluconazole: 12.9-16.5%; topicals, efinaconazole: 3.2-13.8%); over 30% of treated patients received a combination regimen or experienced switching of treatments. Prescribing patterns did not significantly differ in vulnerable patient groups such as elderly patients and in patients with concomitant tinea pedis. Patients receiving a topical and/or oral antifungal prescription were frequently not tested to confirm the onychomycosis diagnosis (76.9%).

Conclusion

Our findings add to a growing body of literature calling for the improvement of onychomycosis management practices.

Treatment of Onychomycosis and the Drug-Drug Interactions in Patients with Diabetes Mellitus and Diabetic Foot Syndrome: A Systematic Review

Background: This systematic review reports on treatments for onychomycosis in patients with diabetes and the drug interactions with other drugs in regard to the complicated diabetic patient profile. Methods: The recommendations in the preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist were applied and the included studies were evaluated using the Consolidated Standards of Reporting Trials (CONSORT) statement and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Searches were conducted in November 2023, using the PubMed (Medline), Scopus, Cochrane Library, and Web of Science databases; studies on antifungal treatments for onychomycosis in patients with diabetes were included. Two authors performed the study selection and data extraction, and any discrepancies between the two reviewers were resolved through discussions with a third reviewer. This review was registered in PROSPERO (CRD42023442107). Results: The systematic review included 10 studies that met the selection criteria. Mycological cures for mild to moderate onychomycosis were: Ageratina pichinchensis (8.6%), 8% ciclopirox (8.6% 24 weeks and 54.3% 48 weeks), 10% efinaconazole (56.5-58.33%), terbinafine (73-76.6%), itraconazole (88.2%), and laser therapy (43.8%). No serious adverse effects or drug interactions were observed because patients with major complications, such as peripheral vascular disease, diabetic neuropathy, liver and renal dysfunction, poorly controlled diabetes, and severe onychomycosis, were excluded. Conclusions: The antifungal treatments described in the included studies are safe for patients with well-controlled diabetes, but there are currently no studies involving patients with diabetes and multiple complications, such as diabetic foot syndrome or severe onychomycosis. Thus, further research is needed in terms of this patient profile.

"Unveiling onychomycosis: Pathogenesis, diagnosis, and innovative treatment strategies"

Onychomycosis, a widespread fungal nail infection, manifests as discoloration, thickening, and detachment of nails, often affecting the surrounding skin. While dermatophytes were historically considered the primary causative agents, recent studies reveal a rise in non-dermatophyte mold (NDM) infections, particularly in warmer climates. Dermatophytes dominate toenail infections, while yeasts and molds also contribute to fingernail infections, with certain molds like Fusarium spp. and Scytalidium spp being notable culprits. Diagnostic challenges arise from elevated false-negative rates in conventional methods like microscopy and culture, particularly with NDM infections. Histology and polymerase chain reaction (PCR) offers higher accuracy, albeit requiring multiple confirmations due to contamination risks. Treatment options encompass oral antifungals with higher cure rates but significant side effects and topical treatments with milder side effects but inferior efficacy. Several ongoing research aims to enhance transungual delivery through various approaches for the treatment of onychomycosis. Recurrence rates underscore the importance of prompt treatment, footwear hygiene, and preventive measures like topical treatments to mitigate the risk of reinfection. Understanding the evolving fungal landscape in onychomycosis is critical for effective management and recurrence prevention strategies.

Demographic and Pathogen Profiles of Superficial Fungal Infections-A Single-Centre Observational Study in Poland

BACKGROUND

Superficial fungal infections (SFI) are contagious conditions affecting the skin and its appendages, caused by various fungal species. Monitoring the distribution of common pathogens and identifying at-risk patient groups are essential for effective management and prevention.

OBJECTIVES

This study investigates the characteristics of SFI in Poland's Malopolska region from 2017 to 2019, focusing on etiological agents, infection sites and risk factors.

PATIENTS/METHODS

A retrospective analysis was conducted on 4522 mycological cultures from 3594 patients, incorporating demographic data (age, sex), sample sites and mycological test results.

RESULTS

Among the 1175 positive mycological tests recorded from 959 patients, Trichophyton rubrum-primarily affecting toenails and feet-and Candida albicans-mainly targeting fingernails-were the most common pathogens across all age groups. Children exhibited a higher incidence of infections caused by Microsporum canis, Malassezia furfur and T. mentagrophytes. In contrast, Scopulariopsis brevicaulis was more frequently identified in individuals over 60 years old.

CONCLUSIONS

The observed trends in SFI characteristics at our centre during the pre-pandemic period align with global epidemiological data. However, further studies are warranted to address existing gaps in understanding the epidemiology of SFI and to refine preventive and therapeutic strategies.

Dermatophytes: Update on Clinical Epidemiology and Treatment

Dermatophytes represent the largest and most common group of fungal infections, impacting 25% of the global population. Among them, Trichophyton rubrum has emerged as the predominant species, responsible for a range of conditions such as tinea corporis, tinea pedis, onychomycosis, tinea cruris, and tinea manuum. Although dermatophyte incidence varies geographically, there is a noticeable rise in cases caused by T. indotineae, a strain that exhibits resistance to terbinafine. In the past decade zoophilic dermatophyte T. mentagophytes genotype VII (now known as T. interdigitale) gains a growing importance, due to its increasing frequency, the severity of the clinical manifestation and mode of transmission. Tinea infections present with various clinical symptoms and can affect individuals of all ages, from tinea pedis in adults to tinea capitis in children. Among adults globally, tinea unguium (onychomycosis) is the most common form of dermatophytosis, affecting 5.5% of the general population. Tinea unguium is more frequently seen in developed countries, while tinea capitis is more common in developing nations. The COVID-19 pandemic has led to an increase in cases of tinea faciei, likely due to prolonged mask-wearing. Terbinafine remains the preferred treatment for dermatophyte infections worldwide due to its potent fungicidal properties, minimal risk of drug interactions, and fewer side effects compared to other oral antifungals. Itraconazole and terbinafine appear to be equally effective and safe for treating tinea cruris and tinea corporis. However, the rising resistance of dermatophytes to these antifungal drugs, along with frequent recurrences of dermatophytosis in certain regions, is becoming a significant public health concern.

Pediatric Nail Disorders

Background

Pediatric nail disorders encompass a broad range of conditions. This article aimed to consolidate current knowledge on pediatric nail disorders to enhance diagnostic proficiency and clinical management among healthcare professionals.

Summary

Pediatric nail disorders present a diagnostic challenge due to their diverse nature. Non-syndromic congenital nail disorders encompass various anomalies such as anonychia/hyponychia, congenital malalignment of the great toenail, and racket thumbs, each with distinct clinical presentations and genetic associations. Syndromic congenital nail disorders, often part of complex syndromes, are characterized by unique features and associated abnormalities. Acquired nail diseases in children, like Beau's lines and onychomadesis, typically result from trauma or infection, while melanonychia, although rare in children, requires careful monitoring for potential malignant alterations, with consideration for biopsy in cases with concerning features.

Key Messages

(1) Pediatric nail disorders may pose diagnostic challenges and require a comprehensive understanding of nail anatomy and development. (2) Congenital nail disorders encompass isolated anomalies and syndromic associations, necessitating thorough evaluation for associated systemic conditions. (3) Acquired nail diseases may indicate underlying trauma or systemic illness and require careful assessment.(4) Melanonychia in children requires ongoing monitoring and evaluation, emphasizing the importance of consistent follow-up and histopathological examination when necessary.

Soft nanoparticles as antimicrobial agents and carriers of microbiocides for enhanced inhibition activity

Antibiotic resistance continues to pose significant health challenges. Considering severe limitations in the discovery and supply of new antibiotics, there is an unmet need to design alternative and more effective strategies for addressing this global issue. Use of polymeric nanoparticles with cationic shell surfaces offers a highly promising approach to coupling their inherent bactericidal action with sustained delivery of small lipophilic microbicides. We have utilized this platform for assembling multi-tasking soft core-shell nanoparticles from star polymers with the desired asymmetric arm composition. These stable nanoparticles with low critical micelle concentration imparted intrinsic antimicrobial potency due to high positive charge density in the corona, as well as the loading of active biocidal agents (such as curcumin and terbinafine) for potential dual and coadjuvant inhibition. This strategic combination allows for both immediate (direct contact) and extended (drug delivery) antibacterial activities for better therapeutic efficacy. Micellar nanoparticles with and without therapeutic cargo were highly efficient against both Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), representative Gram-negative and Gram-positive bacteria, respectively. Interestingly, we observed bacteria- and concentration-dependent effects, in which higher concentrations of charged nanoparticles were more effective against E. coli, whereas B. subtilis was inhibited only at lower concentrations. This work highlights a valuable platform to achieve combination therapy through nanoparticles with charged coronas and delivery of potent therapeutics to overcome antimicrobial resistance.

Diagnostic Accuracy of Dermatoscopy Versus Microbiological Culture and Polymerase Chain Reaction in the Diagnosis of Onychomycosis: A Cross-Sectional Study

BACKGROUND

Several clinical signs in dermatoscopy are very characteristic of onychomycosis and can be a quick complement for the diagnosis of onychomycosis.

OBJECTIVES

The aim of this study was to evaluate the diagnostic accuracy of dermatoscopy compared to microbiological culture and polymerase chain reaction (PCR), as well as the clinical signs associated with onychomycosis.

METHODS

The clinical signs of 125 patients were assessed cross-sectionally using dermatoscopy, and a positive or negative result was assigned. A sample was then taken for PCR and microbiological culture.

RESULTS

Of the 125 patients, 69.6% (87/125) had positive results when both laboratory tests were combined. When they were not combined, the prevalence was lower at 48% (60/125) with PCR and at 43.2% (54/125) with culture. Furthermore, 76.8% (96/125) were classified as positive with dermatoscopy with a sensitivity of 1, a specificity of 0.76, positive predictive value of 0.91 and negative predictive value of 1 (with 95% confidence intervals). Of the 96 dermatoscopy-positive samples, 36 were negative with PCR (p < 0.001), 42 were negative with culture (p < 0.001) and nine were negative when both tests were combined (p < 0.001). Clinical signs that were significantly associated with the presence of onychomycosis were subungual hyperkeratosis (dermatoscopy: p = 0.004, odds ratio (OR) = 2.438; PCR + microbiological culture: p = 0.004, OR = 3.221), subungual detritus (p = 0.033, OR = 3.01, only with dermatoscopy) and dermatophytoma (dermatoscopy: p = 0.049, OR = 3.02; PCR + microbiological culture: p = 0.022, OR = 2.40).

CONCLUSIONS

The results suggest that dermatoscopy is a good tool for the diagnosis of onychomycosis but should be used as a complementary test or for screening patients to be sampled for laboratory testing. The combination of the three tests can lead to a reduction of false-positive and false-negative clinical and laboratory results. This allows for early diagnosis and specific treatment based on test results.

Transungual Penetration and Antifungal Activity of Prescription and Over-the-Counter Topical Antifungals: Ex Vivo Comparison

INTRODUCTION

Topical antifungals for toenail onychomycosis must penetrate the nail to deliver an inhibitory concentration of free drug to the site of infection. In two ex vivo experiments, we tested the ability of topical antifungals to inhibit growth of Trichophyton rubrum and Trichophyton mentagrophytes, the most common causative fungi in toenail onychomycosis.

METHODS

Seven topical antifungals were tested: three U.S. Food and Drug Administration-approved products indicated for onychomycosis (ciclopirox 8% lacquer; efinaconazole 10% solution; tavaborole 5% solution) and four over-the-counter (OTC) products for fungal infections (tolnaftate 1% and/or undecylenic acid 25% solutions). The ability to inhibit fungal growth was tested in the presence and absence of keratin. Products were applied either to human cadaverous nails or keratin-free cellulose disks prior to placement on an agar plate (radius: 85 mm) seeded with a clinical isolate of T. rubrum or T. mentagrophytes. After incubation, the zone of inhibition (ZI), defined as the radius of the area of no fungal growth, was recorded.

RESULTS

In the nail penetration assay, average ZIs for efinaconazole (T. rubrum: 82.1 mm; T. mentagrophytes: 63.8 mm) were significantly greater than those for tavaborole (63.5 mm; 39.1 mm), ciclopirox (7.4 mm; 3.6 mm) and all OTC products (range: 10.5-34.2 mm against both species; all P < 0.001). In the cellulose disk diffusion assay, efinaconazole and tavaborole demonstrated maximal antifungal activity against both species (ZIs = 85 mm); average ZIs against T. rubrum and T. mentagrophytes were smaller for ciclopirox (59.0 and 55.7 mm, respectively) and OTC products (range: 31.2-57.8 mm and 25.7-47.7 mm, respectively).

CONCLUSIONS

Among all antifungals tested, the ability to penetrate human toenails to inhibit growth of both T. rubrum and T. mentagrophytes was greatest for efinaconazole, followed by tavaborole. These results indicate superior transungual penetration of efinaconazole compared to the other antifungals, suggesting lower keratin binding in the nail.

[Dermatomycoses: topical and systemic antifungal treatment]

Topical antifungals with activity against dermatophytes include amorolfine, allylamines, azoles, ciclopiroxolamine, and tolnaftate. Polyene antimycotics, such as amphotericin B and nystatin, alternatively, miconazole are suitable for yeast infections of the skin and mucous membranes. For severe yeast infections of the skin and mucous membranes, oral triazole antimycotics, such as fluconazole and itraconazole, are used. Pityriasis versicolor is treated topically with antimycotics, and in severe forms also orally with itraconazole, alternatively fluconazole. Terbinafine, itraconazole and fluconazole are currently available for the systemic treatment of severe dermatophytoses, tinea capitis and onychomycosis. In addition to proven therapeutic regimens, unapproved (off-label use) intermittent low-dose therapies are increasingly being used, particularly in onychomycosis. Oral antimycotics for the treatment of tinea capitis and onychomycosis in children and adolescents can only be used off-label in Germany. In general, any oral antifungal treatment should always be combined with topical antifungal therapy. In tinea corporis and tinea cruris caused by Trichophyton (T.) mentagrophytes ITS (internal transcribed spacer) genotype VIII (T. indotineae), there is usually terbinafine resistance. Identification of the species and genotype of the dermatophyte and resistance testing are required. The drug of choice for T. mentagrophytes ITS genotype VIII dermatophytoses is itraconazole. In individual cases, treatment-refractory onychomycosis may be due to terbinafine resistance of T. rubrum. Here too, resistance testing and alternative treatment with itraconazole should be considered. Therapy monitoring should be carried out culturally and, if possible, using molecular methods (polymerase chain reaction). Alternative treatment options include laser application, and photodynamic therapy (PDT).

Safety and efficacy of new generation azole antifungals in the management of recalcitrant superficial fungal infections and onychomycosis

INTRODUCTION

Terbinafine is considered the gold standard for treating skin fungal infections and onychomycosis. However, recent reports suggest that dermatophytes are developing resistance to terbinafine and the other traditional antifungal agents, itraconazole and fluconazole. When there is resistance to terbinafine, itraconazole or fluconazole, or when these agents cannot used, for example, due to potential drug interactions with the patient's current medications, clinicians may need to consider off-label use of new generation azoles, such as voriconazole, posaconazole, fosravuconazole, or oteseconazole. It is essential to emphasize that we do not advocate the use of newer generation azoles unless traditional agents such as terbinafine, itraconazole, or fluconazole have been thoroughly evaluated as first-line therapies.

AREAS COVERED

This article reviews the clinical evidence, safety, dosage regimens, pharmacokinetics, and management algorithm of new-generation azole antifungals.

EXPERT OPINION

Antifungal stewardship should be the top priority when prescribing new-generation azoles. First-line antifungal therapy is terbinafine and itraconazole. Fluconazole is a consideration but is generally less effective and its use may be off-label in many countries. For difficult-to-treat skin fungal infections and onychomycosis, that have failed terbinafine, itraconazole and fluconazole, we propose consideration of off-label voriconazole or posaconazole.

Tinea Incognito

Tinea incognito (TI), or incognita, are superficial fungal dermatophyte infections that are changed in shape, most frequently because of topical, systemic steroids use and other immunosuppressants. There are different clinical presentations depending on host factors and the species of dermatophyte causing the disorder. Diagnosis can be challenging and might need combined methods. Once diagnosed the treatment is the usual antifungals, either topical or systemic or combined depending on the site, extent, and host factors.

Time to Think Antifungal Resistance Increased Antifungal Resistance Exacerbates the Burden of Fungal Infections Including Resistant Dermatomycoses

Increased antifungal resistance is exacerbating the burden of invasive fungal infections, as well as potentially contributing to the increase in resistant dermatomycoses. In this commentary, we focus on antifungal drug resistance, in contrast to antibacterial resistance. We provide a brief historical perspective on the emergence of antifungal resistance and propose measures for combating this growing health concern. The increase in the incidence of invasive and cutaneous fungal infections parallels advancements in medical interventions, such as immunosuppressive drugs, to manage cancer and reduce organ rejection following transplant. A disturbing relatively new trend in antifungal resistance is the observation of several fungal species that now exhibit multidrug resistance (eg, Candida auris, Trichophyton indotineae). Increasing awareness of these multidrug-resistant species is paramount. Therefore, increased education regarding potential fungus-associated infections is needed to address awareness in the general healthcare setting, which may result in a more realistic picture of the prevalence of antifungal-resistant infections. In addition to education, increased use of diagnostic tests (eg, micro and macro conventional assays or molecular testing) should be routine for healthcare providers facing an unknown fungal infection. Two critical barriers that affect the low rates for Antifungal Susceptibility Testing (AST) are low (or a lack of) sufficient insurance reimbursement rates and the low number of qualified laboratories with the capacity to perform AST. The ultimate aim is to improve the quality of patient care through fungal identification, diagnosis, and, where appropriate, susceptibility testing. Here we propose an all-encompassing call to action to address this emerging challenge.