Candida Onychomycosis: an Old Problem in Modern Times

Molecular identification and antifungal susceptibility profile of rare and emerging yeast species causing onychomycosis

OBJECTIVES

Onychomycosis is a nail infection caused by various fungal agents. In recent years, there has been an increase in cases of onychomycosis caused by rare fungi, which are often challenging to identify using conventional methods. Sometimes, these unusual species exhibit different antifungal susceptibility patterns compared to more common yeast species. Therefore, this study aimed to identify rare yeast species causing onychomycosis and assess their antifungal susceptibility profiles.

RESULTS

Nineteen rare and emerging yeast isolates, representing seven species, including Candida orthopsilosis (n = 9, 47.36%), Clavispora lusitaniae (formerly Candida lusitaniae) (n = 2, 10.52%), Wickerhamiella pararugosa (formerly Candida pararugosa) (n = 2, 10.52%), Naganishia diffluens (formerly Cryptococcus diffluens) (n = 2, 10.52%), Wickerhamomyces anomalus (n = 2, 10.52%), Cyberlindnera fabianii (n = 1, 5.26%), and Meyerozyma caribbica (formerly Candida fermentati) (n = 1, 5.26%), were identified. Most rare yeast agents exhibited high minimum inhibitory concentration (MIC) values for fluconazole.

A case report of childhood onychomycosis caused by the rare yeast Kodamaea ohmeri

Onychomycosis is an uncommon disease in pediatric patients with dermatophytes and Candida spp. being the main causative agents. Kodamaea ohmeri has recently emerged as a human pathogen, including an onychomycosis causative agent. Here, we report the first case of childhood onychomycosis caused by K. ohmeri in Vietnam, presenting clinically as a white superficial onychomycosis. Fungal identification was confirmed by sequencing of the ITS1-2 region. Antifungal susceptibility testing revealed low minimum inhibitory concentrations for all tested agents, except fluconazole and caspofungin. The patient was treated with 2 % ketoconazole cream one month, resulting in complete resolution of the nail damage with no relapse observed after six months.

"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.

The refractory nailbed ulceration caused by Candida parapsilosis after nail extraction

An 82-year-old female patient presented to our clinic with refractory nailbed ulceration accompanied by pain in her left fourth toe. Six months prior, she had undergone nail removal surgery to address a persistent paronychia that had not resolved for four months. Crust, necrotic tissue, and secretion on the nailbed were taken for microbiological examination, and Candida parapsilosis was discovered in culture. The authors first report one refractory nailbed ulceration caused by Candida parapsilosis after nail extraction.

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.

Reactive oxygen and nitrogen species are crucial for the antifungal activity of amorolfine and ciclopirox olamine against the dermatophyte Trichophyton interdigitale

Onychomycosis is a nail infection caused by Trichophyton interdigitale and other fungi, which can be treated with topical amorolfine (AMR) and ciclopirox olamine (CPX). Although these drugs are widely used, little is known about the role of reactive oxygen (ROS) and nitrogen (RNS) in their mechanism of action. Aiming to better understand the effects of AMR and CPX in dermatophytes, we evaluated whether they act through the production of ROS and peroxynitrite (PRN). We tested a set of strains, all susceptible to AMR and CPX, and these antifungals significantly reduced T. interdigitale viability within 24 hours. This effect occurred concomitantly with reduced ergosterol, increased production of ROS and PRN, and consequently increased lipid peroxidation. Together, these mechanisms lead to cell damage and fungal death. These fungicidal effects were abolished when PRN and superoxide scavengers were used in the assays, demonstrating the role of these species in the mechanism of action. We also studied the antioxidant system when T. interdigitale was exposed to AMR and CPX. Interestingly, superoxide dismutase and catalase inhibition lead to altered ROS and PRN production, lipid peroxidation, and ergosterol levels. In fact, the combination of AMR or CPX with a superoxide dismutase inhibitor was antagonistic. Together, these data demonstrate the importance of ROS and PRN in the antifungal action of AMR and CPX against the evaluated T. interdigitale strains.

Antifungal activity of 2-Chloro-N-phenylacetamide, docking and molecular dynamics studies against clinical isolates of Candida tropicalis and Candida parapsilosis

AIMS

This study evaluated the antifungal, antibiofilm, and molecular docking of 2-Chloro-N-phenylacetamide against clinical isolates of Candida tropicalis and Candida parapsilosis.

METHODS AND RESULTS

MIC of the test drugs was determined by microdilution. A1Cl obtained MIC values ranging from 16 and 256 μg/mL. Fluconazole MIC ranging from 16 and 512 μg/mL. MIC of A1Cl showed fungicide activity, emphasizing the solid antifungal potential of this drug. An association study was performed with A1Cl and fluconazole (checkerboard), revealing indifference by decreasing. Thus, we conducted this study using A1Cl isolated. In the micromorphological assay, the test drugs reduced the production of virulence structures compared to the control (concentration-dependent effect). A1Cl inhibited in vitro biofilm formation at all concentrations tested (1/4MIC to 8xMIC) (p<0.05) and reduced mature biofilm biomass (p<0.05) against C. tropicalis and C. parapsilosis. In the ex vivo biofilm susceptibility testing (human nails fragments), A1Cl inhibited biofilm formation and reduced mature biofilm biomass (p<0.05) more than 50% at MIC. Fluconazole had a similar effect at 4xMIC. In silico studies suggest that the mechanism of antifungal activity of A1Cl involves the inhibition of the enzyme dihydrofolate reductase rather than geranylgeranyltransferase-I.

CONCLUSIONS

The results suggest that A1Cl is a promising antifungal agent. Furthermore, this activity is related to attenuation of expression of virulence factors and antibiofilm effects against C. tropicalis and C. parapsilosis.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our study provides the first evidence that A1Cl, a novel synthetic drug, has fungicidal effects against C. tropicalis and C. parapsilosis. Furthermore, in vitro and ex vivo biofilms assays have demonstrated the potential antibiofilm of A1Cl. The mechanism of action involves inhibiting the enzyme dihydrofolate reductase, which was supported by in silico analyses. Therefore, this potential can be explored as a therapeutic alternative for onychomycosis and, at the same time, contribute to decreasing the resistance of clinical isolates of C. tropicalis and C. parapsilosis.

Coexistence of onychomycosis and nail psoriasis and its correlation with systemic treatment

BACKGROUND

Epidemiological studies indicate that onychomycosis may affect up to 79% of psoriatic patients. Onychomycosis in psoriatic patients is more commonly caused by yeasts comparing with non-psoriatic.

OBJECTIVES

Evaluate the prevalence of fungi in nail psoriasis. Evaluate the association between direct mycological examination (DME) and mycological culture, Nail Psoriasis Severity Index (NAPSI) and systemic treatment for psoriasis.

METHODS

Of 133 nails from 20 patients with nail psoriasis were evaluated as follows: 9 patients were using topical treatment and 11 were on systemic treatment. The assessment of psoriasis severity using NAPSI was performed in all psoriatic nails. The presence of fungi was confirmed in DME and culture.

RESULTS

DME showed the presence of fungal elements in 45 nails (33.83%) with a predominance of blastoconidia (95.5%) No septate hyphae were seen. Mycological culture was positive in 36 (27.06%) samples. Among them, Candida grew in 31 (86.1%): Candida parapsilosis in 15 (48.38%), Candida spp in 14 (45.16%). No growth of dermatophytes was observed. Patients with systemic treatment showed a higher frequency of positive test (DME and culture) for fungi when compared to topic treatment (p:.006). There was a positive correlation between NAPSI, mycological culture and systemic treatment (p:.0063); the risk was four times higher (OR:4.0).

LIMITATION OF THE STUDY

Sample size.

CONCLUSION

These results are consistent with some previous reports, Candida was the fungus with higher frequency on the psoriatic nails, however, the role of these fungi is controversial (contamination x colonisation x infection). The fact that the immunosuppressive treatment increases the chance of fungal infection leads us to a greater attention to this patient profile, to prevent the intensification of nail psoriasis (Köbner phenomenon).

Polishing the Therapy of Onychomycosis Induced by Candida spp.: Amphotericin B-Loaded Nail Lacquer

Onychomycosis induced by Candida spp. has several limitations regarding its treatment. Nail lacquers display the potential to overcome these drawbacks by providing therapeutic compliance and increasing local drug bioavailability. Thus, this work aimed to produce a nail lacquer loaded with Amphotericin B (AmB) and evaluate its performance. The AmB-loaded nail lacquer was produced and preliminarily characterized. An AmB quantification method was developed. Stability, drug release, permeability and anti-Candida activity assays were conducted. The analytical method validation met the acceptance criteria. The drug loading efficiency was 100% (0.02 mg/g of total product), whereas the AmB stability was limited to ≅7 days (≅90% remaining). The nail lacquer displayed a drying time of 187 s, non-volatile content of around 20%_w/w, water-resistance of approximately 2%_w/w of weight loss and satisfactory in vitro adhesion. Moreover, the in vitro antifungal activity against different Candida spp. strains was confirmed. The AmB release and the ex vivo permeability studies revealed that AmB leaves the lacquer and permeates the nail matrix in 47.76 ± 0.07% over 24 h. In conclusion, AmB-loaded nail lacquer shows itself as a promising extemporaneous dosage form with remarkable anti-Candida activity related to onychomycosis.