Antifungal Drug Use for Onychomycosis

A Current Diagnostic and Therapeutic Challenge: Tinea Capitis

Tinea capitis is a dermatophyte scalp infection with a marked prevalence among the pediatric population. However, in the last few years, its epidemiology has changed due to increasing population migration worldwide. Host-specific and environmental factors contribute to the pathogenesis of tinea capitis. Clinically, tinea capitis may present as a subtle hair loss accompanied by scalp scaling, alopecia with scaly patches, or alopecia with black dots. A more severe form of tinea capitis is represented by kerion celsi, which clinically presents as a tender plaque covered by pustules and crusts. If left untreated, this dermatophytic infection may resolve with permanent scarring and alopecia. The pathological changes found in tinea capitis are reflected by a spectrum of clinical changes. Zoophilic infections typically prompt an extensive inflammatory reaction, while anthropophilic dermatophytoses often lack inflammation and result in more persistent lesions. Tinea capitis typically requires systemic antifungal therapy. Griseofulvin, terbinafine, itraconazole, and fluconazole are the main antifungal agents used. Currently, the duration of antifungal therapy varies based on the clinical presentation and type of dermatophyte involved. Through the reported cases and literature review, we aim to emphasize the importance of the early recognition of atypical variants of tinea capitis in immunocompetent children for the prompt initiation of systemic antifungal therapy, minimizing the need for prolonged treatment. Additionally, we emphasize the importance of regular laboratory testing during systemic antifungal therapy, particularly liver enzyme tests, to prevent adverse events, especially in cases requiring long-term treatment.

Species distribution and antifungal susceptibility profiles of yeasts isolated from onychomycosis: a cross-sectional study with insights into emerging species

Candida onychomycosis is a common fungal infection affecting the nails, primarily caused by Candida (C.) species. Regarding the increasing trend of Candida onychomycosis and the antifungal resistant phenomenon in recent years, this study aims to evaluate the epidemiological characteristics of Candida onychomycosis, the distribution of emerging species, and the antifungal susceptibility profiles of isolates. Onychomycosis caused by yeast species was confirmed through direct examination and culture of nail scraping among all individuals suspected to have onychomycosis and referred to a medical mycology laboratory between June 2019 and March 2022. Species of yeast isolates were identified using the multiplex PCR and PCR-RFLP methods. The antifungal susceptibility of isolates to common antifungal agents and imidazole drugs was evaluated according to the M-27-A3 CLSI protocol. Among 101 yeast strains isolated from onychomycosis, Candida parapsilosis complex (50.49%) was the most common species, followed by C. albicans (20.79%) and C. tropicalis (10.89%). Rare species of yeasts such as C. guilliermondii and Saccharomyces cerevisiae were also identified by molecular methods. Results obtained from antifungal susceptibility testing showed significant differences in MIC values of isoconazole, fenticonazole, and sertaconazole among different species. Overall, a fluconazole-resistant rate of 3% was found among Candida species. Moreover, there was a statistically significant difference in MICs of fenticonazole and clotrimazole between the two most prevalent causative species, C. parapsilosis complex and C. albicans. Correct identification of the causative agents of onychomycosis and performing susceptibility testing could be helpful in choosing the most appropriate antifungal therapy.

Anti-bacterial effects of functional cosmetics containing silver ions (Ag+ ) on problematic toenails in Republic of Korea

BACKGROUND

Problematic toenails caused by various diseases that are infected by various bacteria are discolored or deformed if left unattended for a long time are gradually increasing in modern society. Accordingly, the present study examines the anti-bacterial effects of LCN products, focused on Pseudomonas aeruginosa and Trichophyton rubrum, which can appear in problematic toenail symptoms. After the treatment, a significant anti-bacterial effect occurring on problematic toenails when a product containing silver ion (Ag⁺ ) will be analyzed.

METHODS

The anti-bacterial activity of LCN functional gel products in anti-fungal and/or anti-bacterial potency was confirmed by the paper disk method against two strains (Pseudomonas aeruginosa and Trichophyton rubum).

RESULTS

From July 2019 to October 2019, 30 men and women in their 20s and 50s who needed to manage problematic toenails in Wonju city, Gangwon-do, Republic of Korea, were asked to use LCN products once every two weeks. After 4 months, changes in the managed toenails were observed. Both products showed very good anti-microbial activity against, Trichophyton rubum but a very weak one against Pseudomonas aeruginosa.

CONCLUSION

As a result of this study, although there was a difference between individuals, the feet treated with LCN products showed effective anti-bacterial activity against topical anti-bacterial effects.

Relevant insights into onychomycosis' pathogenesis related to the effectiveness topical treatment

Onychomycosis (OM) is a fungal infection, responsible for about 50% of nail diseases. OM has been attributed to the ability of fungi to naturally organize themselves into biofilms on nail surfaces. However, little is known about the exact role of the biofilm in the etiopathogenesis of OM, as well as its influence in the permeation of a topical treatment. The objectives of this study were to review the literature for topical OM treatments in clinical trials, assess the efficiency of these treatments, and discuss factors that could affect the success of these treatments. First, a systematic search of articles published in the MEDLINE database (PubMed) between January 2010 and December 2019 was conducted, focusing on drugs under clinical trials for the topical treatment of OM. Of the publications selected, it was clear that none of them had considered the fungi organized in biofilm. Therefore, we reflected on some important variables involved in OM, such as the nail structure and the mechanism of fungal invasion. Some methods, such as histopathologic analysis and spectroscopy techniques, were found to be effective in the detection of nail biofilm, and could be used in future drug permeation studies. This review allowed us to conclude that novel antifungals for the topical treatment of OM must consider the drug to permeate through biofilm. Natural products, such as propolis, seem strong candidates in this respect.

Molecular characterization and antifungal activity against non-dermatophyte molds causing onychomycosis

Onychomycosis is a fungal disease that caused by different types of fungi. Non-dermatophyte molds are a large saprophytic fungi group that live in nature and could affect traumatic nails. The aim of this study was to identify non-dermatophyte molds causing onychomycosis and evaluation of several antifungal activities against the isolates. The samples consisted of 50 non-dermatophyte molds isolated from patients with onychomycosis confirmed by direct and culture examination fungal. DNA was extracted, amplified, and sequenced. Disk diffusion method was used to evaluate itraconazole, fluconazole, ketoconazole, terbinafine, posaconazole, and econazole activity against the isolates. The species identified as: Aspergillus flavus 22 (44%), A. niger 12 (24%), A. fumigates, 3 (6%), A. sydowii 3 (6%), A. terreus 1 (2%), Penicillium commune 2 (4%), P. glabrum 2 (4%), P. chrysogenum, 1 (2%), Fusarium solani 3 (6%) and F. thapsinum 1 (2%). Most of the samples were sensitive to terbinafine, itraconazole, and econazole and 94% of the isolates were resistant to fluconazole. This study showed that Aspergillus species were the most common cause of non-dermatophyte mold onychomycosis and fluconazole was the most resistant antifungals. Care must be taken to choose the appropriate antifungal drug for a better cure.

Nail dermatophytoma in HIV-infected patients in Cali, Colombia

INTRODUCTION

A dermatophytoma is a mass of hyphae that is observed at direct examination, it responds poorly to treatment with antifungal drugs, some authors have proposed that it is actually a biofilm. This pathology is underdiagnosed, and its true incidence is unknown.

OBJECTIVES

This study presents the clinical findings of dermatophytoma in HIV/AIDS patients from Colombia presenting onychomycosis.

MATERIAL AND METHODS

A transversal observational descriptive study was carried out in a third level university hospital. One hundred thirty HIV positive patients diagnosed using ELISA and Western Blot that presented nail lesions on their hands and/or feet compatible with onychomycosis were included. Samples taken from affected nails were observed in direct examination with KOH and seeded onto Sabouraud agar, mycosel agar and dextrose-potato agar. Molds were identified based on macroscopic and microscopic characteristics.

RESULTS

Six (4.6%) individuals presented dermatophytoma. Average age was 43 years (range 33-50); nails more commonly affected (5/6) were on the toes, principally the hallux. Clinical manifestations included a yellow or white, rounded or linear dense area on the nail. Superficial white onychomycosis was present in 83.3% of the patients. Fungal cultures were obtained in only 5 patients; Trichophyton mentagrophytes complex was found in 2 individuals while T. rubrum, T. tonsurans and Epidermophyton floccosum were in the other 3. Average cell count for CD4⁺T lymphocytes was 86.8 cells/mm³ (range 9-282).

CONCLUSIONS

This is the first report in Colombia of dermatophytoma in HIV/AIDS patients, most of them had a CD4+ T lymphocytes count less than 200 cells/mm3. Several clinical forms of onychomycosis were observed, the most frequent was the white superficial onychomycosis.

In Vitro Resistance and Evolution of Resistance to Tavaborole in Trichophyton rubrum

Tavaborole is currently used in the topical treatment of onychomycosis. In this study, we analyzed the in vitro emergence/evolution of resistance against tavaborole in Trichophyton rubrum When T. rubrum strains were propagated on media containing the MIC of tavaborole, spontaneous resistant mutants were isolated at a frequency of 10^-8 The frequency was almost 100-fold higher following fungal growth in the presence of a subinhibitory tavaborole concentration (0.5-fold the MIC) for 10 transfers. All collected mutants showed similar 4- to 8-fold increases in the drug MIC. No cross-resistance to other antifungals was evident.

Evaluation of susceptibility and response in the surface of agents of surface mycoses (Trichophyton mentagrophytes; T. tonsurans) to antifungal drugs of interest in a medical clinic

Introduction: The resistance of fungal species to drugs usually used in clinics is of great interest in the medical field. Objective: To evaluate susceptibility and in vitro response of species of Trichophyton spp. to antifungal drugs of interest in clinical medicine. Methods: 12 samples of clinical isolates from humans were used, nine of T. mentagrophytes and three of T. tonsurans. Susceptibility tests were performed according to the agar diffusion (AD) and broth microdilution (BM) methods. Results: In the AD method, the species T. tonsurans presented a percentage of sensitivity of 33% in relation to amphotericin B and 66% to itraconazole, with 100% resistance to ketoconazole and fluconazole. T. mentagrophytes also showed 100% resistance to ketoconazole in this technique, with 11% sensitivity to ketoconazole, 22% to itraconazole and 22% of samples classified as sensitive dose dependent. In the MC method, the species T. tonsurans presented a sensitivity percentage of 66%, 55% and 33% in relation to ketoconazole, fluconazole and itraconazole, respectively. The T. mentagrophytes species presented sensitivity percentages of 11%, 11%, 33% and 55% for amphotericin B, itraconazole, ketoconazole and fluconazole, respectively. Conclusion: There was resistance in vitro of the species of T. mentagrophytes and T. tonsurans against the antifungal fluconazole and relative resistance against ketoconazole in the AD method. In BM, however, important percentages of sensitivity were observed for the two species analyzed in relation to the antifungals fluconazole and ketoconazole when compared to itraconazole and amphotericin B.

Synthesis and Influence of 3-Amino Benzoxaboroles Structure on Their Activity against Candida albicans

Benzoxaboroles emerged recently as molecules of high medicinal potential with Kerydin® (Tavaborole) and Eucrisa® (Crisaborole) currently in clinical practice as antifungal and anti-inflammatory drugs, respectively. Over a dozen of 3-amino benzoxaboroles, including Tavaborole's derivatives, have been synthetized and characterized in terms of their activity against Candida albicans as a model pathogenic fungus. The studied compounds broaden considerably the structural diversity of reported benzoxaboroles, enabling determination of the influence of the introduction of a heterocyclic amine, a fluorine substituent as well as the formyl group on antifungal activity of those compounds. The determined zones of the growth inhibition of examined microorganism indicate high diffusion of majority of the studied compounds within the applied media as well as their reasonable activity. The Minimum Inhibitory Concentration (MIC) values show that the introduction of an amine substituent in position "3" of the benzoxaborole heterocyclic ring results in a considerable drop in activity in comparison with Tavaborole (AN2690) as well as unsubstituted benzoxaborole (AN2679). In all studied cases the presence of a fluorine substituent at position para to the boron atom results in lower MIC values (higher activity). Interestingly, introduction of a fluorine substituent in the more distant piperazine phenyl ring does not influence MIC values. As determined by X-ray studies, introduction of a formyl group in proximity of the boron atom results in a considerable change of the boronic group geometry. The presence of a formyl group next to the benzoxaborole unit is also detrimental for activity against Candida albicans.

Onychomycosis: An Updated Review

Background: Onychomycosis is a common fungal infection of the nail.

Objective: The study aimed to provide an update on the evaluation, diagnosis, and treatment of onychomycosis.

Methods: A PubMed search was completed in Clinical Queries using the key term “onychomycosis”. The search was conducted in May 2019. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews published within the past 20 years. The search was restricted to English literature. Patents were searched using the key term “onychomycosis” in www.freepatentsonline.com.

Results: Onychomycosis is a fungal infection of the nail unit. Approximately 90% of toenail and 75% of fingernail onychomycosis are caused by dermatophytes, notably Trichophyton mentagrophytes and Trichophyton rubrum. Clinical manifestations include discoloration of the nail, subungual hyperkeratosis, onycholysis, and onychauxis. The diagnosis can be confirmed by direct microscopic examination with a potassium hydroxide wet-mount preparation, histopathologic examination of the trimmed affected nail plate with a periodic-acid-Schiff stain, fungal culture, or polymerase chain reaction assays. Laboratory confirmation of onychomycosis before beginning a treatment regimen should be considered. Currently, oral terbinafine is the treatment of choice, followed by oral itraconazole. In general, topical monotherapy can be considered for mild to moderate onychomycosis and is a therapeutic option when oral antifungal agents are contraindicated or cannot be tolerated. Recent patents related to the management of onychomycosis are also discussed.

Conclusion: Oral antifungal therapies are effective, but significant adverse effects limit their use.Although topical antifungal therapies have minimal adverse events, they are less effective than oral antifungal therapies, due to poor nail penetration. Therefore, there is a need for exploring more effective and/or alternative treatment modalities for the treatment of onychomycosis which are safer and more effective.

Pediatric nail disorders: a review

PURPOSE OF REVIEW

Nail disorders represent an uncommon subset of complaints seen in pediatric dermatology. There is a wide array of disorders that can affect the nail unit in children, including infectious, inflammatory, neoplastic, congenital, and traumatic processes. In order to enhance familiarity with pediatric nail conditions, we review the background and treatment of the more common entities seen in pediatric onychology, including onychomycosis, onychomadesis, nail psoriasis, trachyonychia, longitudinal melanonychia, onychophagia, and onychocryptosis.

RECENT FINDINGS

Nail involvement in pediatric patients with psoriasis may indicate increased risk for both overall disease severity and the development psoriatic arthritis. In the evaluation of longitudinal melanonychia, the clinical findings that raise concern for subungual melanoma in adults are often found in benign nail unit nevi in children. In the systemic treatment of pediatric onychomycosis, new data raises the possibility that laboratory monitoring may be approached differently. In the approach to onychophagia, emerging pharmacotherapies include N-acetylcysteine.

SUMMARY

Most nail disorders in pediatric patients have an overall favorable prognosis. However, nail abnormalities can lead to patient and parental anxiety, decreased quality of life, pain, and functional impairment. Clinicians should be aware of these more common diverse entities in order to identify them and apply state of the art management for these issues. Additionally, the reader will learn factors related to these nail disorders, which may require systemic work-up and/or specialist referral.

Activity of Metal-Azole Complexes Against Biofilms of Candida albicans and Candida glabrata

Background:

Onychomycosis is a chronic nail infection caused by fungi frequently resistant to antifungal treatments. Recalcitrance in nail infections is a result of reduced antifungal penetration due to biofilm formation, combined with poor patient compliance with the treatment, which can be as long as 18 months.

Objective:

Metal-drug complexation is a widely used strategy to increase drug efficacy. Therefore, the aim of this work was to evaluate the antifungal and anti-biofilm activity of several metal-azole complexes against Candida albicans and Candida glabrata.

Methods:

Susceptibility assays and scanning electron microscopy were performed to determine the anti-biofilm activity of eight metal-azole complexes in vitro and ex-vivo, using human nail fragments.

Results:

In vitro susceptibility assays showed that complexation of both Au(I) and Zn(II) to clotrimazole and ketoconazole improved the anti-biofilm activity compared to the azole alone. Using an ex-vivo model of biofilm formation on fragments of human nails, we also demonstrate the improved efficacy of metal-azole complexes against biofilms of C. albicans and C. glabrata that resembles the onychomycosis structure. Noteworthy, biofilms of C. glabrata were more susceptible to the optimized complexes than those of C. albicans.

Conclusion:

In conclusion, metal-azole complexes used in this work show promising anti-biofilm activity and further clinical studies should confirm its potential for the treatment of Candida-associated onychomycosis.