Antibiofilm Treatment for Onychomycosis and Chronic Fungal Infections

Combinatorial effect of fluconazole, itraconazole, and terbinafine with different culture extracts of Candida parapsilosis and Trichophyton spp. against Trichophyton rubrum

Onychomycosis is a nail infection caused by dermatophytes, non-dermatophyte fungi, and yeasts, especially Candida species. The present study evaluated the combinatorial effect of different cultured extracts of Candida parapsilosis and Trichophyton mentagrophytes and Trichophyton rubrum with fluconazole, itraconazole, and terbinafine against clinical isolates of Trichophyton rubrum. In addition, investigation of the action of the extracts on the wall or membrane was performed. Pure and mixed cultures of Candida parapsilosis and dermatophytes were filtered through a 0.2-μm membrane and submitted to liquid-liquid extraction using ethyl acetate. After a checkerboard, trial with drugs was performed to evaluate the synergistic interaction with the extract. The results obtained for the minimum inhibitory concentration (MIC) of extracts against the T. rubrum strain in isolation were 500-8000 μg/mL. The MIC range for fluconazole, itraconazole, and terbinafine were 2-32 μg/mL, 0.25-0.5 μg/mL, 0.03-64 μg/mL, respectively. However, when the extract was combined with drugs, the MIC values decreased: extracts 1.9-1000 μg/mL, fluconazole 0.25-4, itraconazole 0.03-0.06 μg/mL, and terbinafine 0.001-0.02 μg/mL. The MIC values of the extracts in the Roswell Park Memorial Institute 1640 medium (RPMI) supplemented with sorbitol did not change, suggesting any action on the cell wall. However, in the presence of RPMI supplemented with ergosterol, MIC values of the extracts increased by up to 2×, indicating action on the fungal cell membrane. A synergistic action was observed between products and drugs, detecting a decrease in MIC values. There is potential and a new therapeutic perspective for fungal control.

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

A growing body of literature has marked the emergence and spread of antifungal resistance among species of Trichophyton, the most prevalent cause of toenail and fingernail onychomycosis in the United States and Europe. We review published data on rates of oral antifungal resistance among Trichophyton species; causes of antifungal resistance and methods to counteract it; and in vitro data on the role of topical antifungals in the treatment of onychomycosis. Antifungal resistance among species of Trichophyton against terbinafine and itraconazole-the two most common oral treatments for onychomycosis and other superficial fungal infections caused by dermatophytes-has been detected around the globe. Fungal adaptations, patient characteristics (e.g., immunocompromised status; drug-drug interactions), and empirical diagnostic and treatment patterns may contribute to reduced antifungal efficacy and the development of antifungal resistance. Antifungal stewardship efforts aim to ensure proper antifungal use to limit antifungal resistance and improve clinical outcomes. In the treatment of onychomycosis, critical aspects of antifungal stewardship include proper identification of the fungal infection prior to initiation of treatment and improvements in physician and patient education. Topical ciclopirox, efinaconazole and tavaborole, delivered either alone or in combination with oral antifungals, have demonstrated efficacy in vitro against susceptible and/or resistant isolates of Trichophyton species, with low potential for development of antifungal resistance. Additional real-world long-term data are needed to monitor global rates of antifungal resistance and assess the efficacy of oral and topical antifungals, alone or in combination, in counteracting antifungal resistance in the treatment of onychomycosis.

Photodynamic inactivation by hypericin-P123 on azole-resistant isolates of the Trichophyton rubrum complex as planktonic cells and biofilm

INTRODUCTION

The Trichophyton rubrum complex comprises the majority of dermatophyte fungi (DM) responsible for chronic cases of onychomycosis, which is treated with oral or topical antifungals. However, owing to antifungal resistance, alternative therapies, such as photodynamic therapy (PDT), are needed. This study investigated the frequency of the T. rubrum species complex in onychomycosis cases in the northwestern region of Paraná state, Brazil, and evaluated the efficacy of (PDT) using P123-encapsulated hypericin (Hyp-P123) on clinical isolates of T. rubrum in the planktonic cell and biofilm forms.

MATERIAL AND METHODS

The frequency of the T. rubrum complex in onychomycosis cases from 2017 to 2021 was evaluated through a data survey of records from the Laboratory of Medical Mycology (LEPAC) of the State University of Maringa (UEM). To determine the effect of PDT-Hyp-P123 on planktonic cells of T. rubrum isolates, 1 × 105 conidia/mL were treated with ten different concentrations of Hyp-P123 and then irradiated with 37.8 J/cm2. Antibiofilm activity of PDT-Hyp-P123 was tested against T. rubrum biofilm in the adhesion phase (3 h), evaluated 72 h after irradiation (37.8 J/cm2), and the mature biofilm (72 h), evaluated immediately after irradiation. In this context, three different parameters were evaluated: cell viability, metabolic activity and total biomass.

RESULTS

The T. rubrum species complex was the most frequently isolated DM in onychomycosis cases (approximately 80 %). A significant reduction in fungal growth was observed for 75 % of the clinical isolates tested with a concentration from 0.19 μmol/L Hyp-P123, and 56.25 % had complete inhibition of fungal growth (fungicidal action); while all isolates were azole-resistant. The biofilm of T. rubrum isolates (TR0022 and TR0870) was inactivated in both the adhesion phase and the mature biofilm.

CONCLUSION

PDT-Hyp-P123 had antifungal and antibiofilm activity on T. rubrum, which is an important dermatophyte responsible for onychomycosis cases.

Antibiofilm Effect of Lavandula multifida Essential Oil: A New Approach for Chronic Infections

Fungal infections are associated with high morbidity and mortality rates, being highly prevalent in patients with underlying health complications such as chronic lung disease, HIV, cancer, and diabetes mellitus. To mitigate these infections, the development of effective antifungals is imperative, with plants standing out as promising sources of bioactive compounds. In the present study, we focus on the antibiofilm potential of Lavandula multifida essential oil (EO) against dermatophyte strains and Candida albicans. The EO was characterized using GC and GC-MS, and its antifungal effect was assessed on both biofilm formation and disruption. Biofilm mass, extracellular matrix, and viability were quantified using crystal violet, safranin, and XTT assays, respectively, and morphological alterations were confirmed using optical and scanning electron microscopy. L. multifida EO showed very high amounts of carvacrol and was very effective in inhibiting and disrupting fungal biofilms. The EO significantly decreased biofilm mass and viability in all tested fungi. In addition, a reduction in dermatophytes' extracellular matrix was observed, particularly during biofilm formation. Morphological alterations were evident in mature biofilms, with a clear decrease in hypha diameter. These promising results support the use of L. multifida EO in the development of effective plant-based antifungal products.

Superficial mycosis, at the site or distant to the surgical site, appears to predispose patients to bacterial periprosthetic joint infections

BACKGROUND

It is traditionally believed that presence of fungal infection in the nail or skin of patients is a risk factor for subsequent infection. The literature is devoid of any evidence to confirm or refute this belief. This study examined a possible relationship between the presence of superficial skin or nail mycoses and subsequent periprosthetic joint infection (PJI) in patients undergoing total joint arthroplasty (TJA).

METHODS

This is a single-centre, retrospective study of patients who underwent primary TJA between 2000 and 2018. 55 patients with superficial mycoses of skin or nail, at the time of arthroplasty were identified and a variable number matching with up to a 1:5 ratio was performed with 182 patients undergoing TJA who had no superficial mycosis. The groups were further divided into knee and hip TJA. The outcome of TJA in the cohorts was compared.

RESULTS

Preoperative demographics were similar between the 2 groups. The incidence of PJI in patients undergoing TKA within a year was significantly higher in patients with superficial mycosis at 8.6% (3/35) compared to 0% (0/120) in patients without mycosis. However, all infections were caused by bacterial species and none were fungal. Multiple regression analysis demonstrated that the presence of superficial mycosis had a strong correlation with development of PJI postoperatively in our TKA cohort.

CONCLUSIONS

Identification of fungal infection (mycosis) of skin and nail in patients awaiting TJA is important. These patients appear to have a higher risk for developing bacterial PJI than those without fungal infections. Further study is needed to determine if treatment of these patients prior to arthroplasty stands to reverse the high risk for PJI that these patients carry.

In vitro and ex vivo antibiofilm activity of riparin 1, and its nor and dinor homologs, against dermatophytes

Dermatophytosis is one of the most frequent superficial mycoses in the world. They are mainly caused by the dermatophytes Trichophyton rubrum and Microsporum canis. Biofilm production is an essential factor in the pathogenesis of dermatophytes; it confers drug resistance and significantly impairs antifungal effectiveness. Therefore, we evaluated the antibiofilm activity of an alkamide-type alkaloid called riparin 1 (RIP1) against clinically relevant dermatophytes. We also produced synthetic nor (NOR1) and dinor (DINOR1) homologs for pharmacological evaluation, with a 61-70% yield. We used in vitro (96-well polystyrene plates) and ex vivo (hair fragments) models to verify the effects of these compounds on the formation and viability of biofilms. RIP1 and NOR1 showed antifungal activity against strains of T. rubrum and M. canis, but DINOR1 showed no significant antifungal activity against the dermatophytes. Furthermore, RIP1 and NOR1 significantly reduced the viability of biofilms in vitro and ex vivo (P < 0.05). RIP1 was more potent than NOR1, possibly due to the distance between the p-methoxyphenyl and the phenylamide moieties in these compounds. Due to the significant antifungal and antibiofilm activities observed for RIP1 and NOR1, we suggest that they could be useful in the treatment of dermatophytosis.

Dermatophytic Biofilms: Characteristics, Significance and Treatment Approaches

Microbes are found in the environment, possibly more often as biofilms than in planktonic forms. Biofilm formation has been described for several important fungal species. The presence of a dermatophytoma in a dermatophytic nail infection was the basis for the proposal that dermatophytes form biofilms as well. This could explain treatment failure and recurrent dermatophytic infections. Several investigators have performed in vitro and ex vivo experiments to study the formation of biofilms by dermatophytes and their properties. The nature of the biofilm structure itself contributes to fungal protection mechanisms against many harmful external agents, including antifungals. Thus, a different approach should be carried out regarding susceptibility testing and treatment. Concerning susceptibility testing, methods to evaluate either the inhibition of biofilm formation, or the ability to eradicate it, have been introduced. As for treatment, in addition to classical antifungal agents, some natural formulations, such as plant extracts or biosurfactants, and alternative approaches, such as photodynamic therapy, have been proposed. Studies that connect the results of the in vitro and ex vivo experimentation with clinical outcomes are required in order to verify the efficacy of these approaches in clinical practice.

Rapid-killing efficacy substantiates the antiseptic property of the synergistic combination of carvacrol and nerol against nosocomial pathogens

Globally, new classes of synthetic and natural antibiotics and antivirulents have continuously been validated for their potential broad-spectrum antagonistic activity with the aim of identifying an effective active molecule to prevent the spread of infectious agents in both food industry and medical field. In view of this, present study is aimed at evaluating the rapid killing efficacy of bioactive molecules Carvacrol (C) and Nerol (N) through British Standard European Norm 1276: phase2/step1 (EN1276) protocol. Active molecules C and N showed broad-spectrum antimicrobial activity against the test strains Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus hirae at concentration range of 78.125, 625, 156.25 and 312.5 μg/mL, respectively, for C, and 625 μg/mL for N. Whereas, combinatorial approach showed efficient activity with four times reduced concentration of C and N at 78.125 and 156.25 µg/mL, respectively, against test strains. Further, EN1276 results proved the rapid killing efficacy of test strains in 1 min of contact time with significant (> 5 log) growth reduction at 100X concentration of actives. SEM analysis and reduced concentration of protease, lipids and carbohydrate contents of treated group biofilm components ascertained preformed biofilm disruption potential of C + N on polystyrene and nail surfaces. C + N at synergistic concentration exhibited no adverse effect on HaCaT cells at 78.125 µg/mL (C) + 156.25 µg/mL (N). Taken together, based on the observed experimental results, present study evidence the antiseptic/disinfectant ability of C + N and suggest that the combination can preferentially be used in foam-based hand wash formulations.

Dermatophytomas: Clinical Overview and Treatment

Dermatophytomas are characterized as a hyperkeratotic fungal mass in the subungual space, showing as dense white or yellow, typically in longitudinal streaks or patches. Masses can be visualized by traditional microscopy or histology. Newer technologies such as dermoscopy and optical coherence tomography also provide visual features for dermatophytoma diagnosis. The density of fungal mass, and lack of adherence to the nail structures, as well as possible biofilm development, may play a role in the reduction in drug penetration and subsequent lack of efficacy with traditional oral therapies such as terbinafine and itraconazole. A combination of drug treatment with mechanical or chemical debridement/avulsion has been recommended to increase efficacy. The topical antifungal solutions such as tavaborole, efinaconazole, and luliconazole may reach the dermatophytoma by both the transungual and subungual routes, due to low affinity for keratin and low surface tension. Current data indicates these topicals may provide efficacy for dermatophytoma treatment without debridement/avulsion. Similarly, fosravuconazole (F-RVCZ) has an improved pharmacological profile versus ravuconazole and may be an improved treatment option versus traditional oral therapies. The availability of improved treatments for dermatophytomas is crucial, as resistance to traditional therapies is on the increase.

Photodynamic Therapy for the Treatment of Fungal Infections

Cutaneous fungal infections are common in humans and are associated with significant physical and psychological distress to patients. Although conventional topical and/or oral anti-fungal medications are commonly recommended treatments, drug resistance has emerged as a significant concern in this patient population, and safer, more efficacious, and cost-effective alternatives are warranted. Recent studies have reported effectiveness of photodynamic therapy (PDT) against fungal infections without severe adverse effects. In this review, we briefly discuss the mechanisms underlying PDT, current progress, adverse effects, and limitations of this treatment in the management of superficial and deep fungal infections.

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.

Hypericin-P123-photodynamic therapy in an ex vivo model as an alternative treatment approach for onychomycosis caused by Fusarium spp

BackgroundFusarium has been considered an opportunistic pathogen, causing several infections in humans, including onychomycosis. In addition, a high resistance to conventional antifungals has been linked to this genus. Photodynamic Therapy (PDT), known as a non-invasive therapy, can be an alternative treatment for fungal infections, based on the excitation of a photosensitizing compound (PS) by a specific length of light, causing damage to the target. The aim of this study was to evaluate the effects of a formulation of Hypericin (Hyp) encapsulated in Pluronic™ (P123), via photodynamic therapy (PDT), on planktonic cells and biofilms in Fusarium spp. using in vitro and ex vivo assays. Materials & Methods epidemiology studies about Fusarium spp. in onychomycosis was perfomed, carried out molecular identification, compared the antifungal activity of the conventional antifungals with PDT with encapsulated Hypericin (Hyp-P123), carried out detection of reactive oxygen species, and measured the antibiofilm effect of the Hyp-P123-PDT in vitro and in an ex vivo model of onychomycosis. Results Hyp-P123-PDT exhibited a fungicidal effect in vitro with reductions ≥ 3 log₁₀. ROS generation increased post-Hyp-P123-PDT in Fusarium spp. Hyp-P123-PDT showed a potent inhibitory effect on adhesion-phase and mature biofilms in vitro tests and an ex vivo model of onychomycosis (p<0.0001). Conclusion Hyp-P123-PDT had a potent effect against Fusarium spp., suggesting that photodynamic therapy with Hyp-P123 is a safe and promising treatment for onychomycosis in clinical practice.

A review of recent research on antifungal agents against dermatophyte biofilms

Dermatophytoses are inflammatory cutaneous mycoses caused by dermatophyte fungi of the genera Trichophyton, Microsporum, and Epidermophyton that affect both immunocompetent and immunocompromised individuals. With therapeutic failure, dermatophytoses can become chronic and recurrent. This is partly due to their ability to develop biofilms, microbial communities involved in a polymeric matrix attached to biotic or abiotic surfaces, contributing to fungal resistance. This review presents evidence accumulated in recent years on antidermatophyte biofilm activity. The following databases were used: Web of Science, Medline/PubMed (via the National Library of Medicine), Embase, and Scopus. Original articles published between 2011 and 2020, emphasizing the antifungal activity of conventional and new drugs against dermatophyte biofilms were eligible. A total of 11 articles met the inclusion criteria and were reviewed - the studies used in vitro and ex vivo (fragments of nails and hair) experimental models. The articles focused on reports of antibiofilm activity for conventional antifungals, natural drugs, and new therapeutic tools. The strains reported on were T. mentagrophytes, T. rubrum, T. tonsurans, M. canis, and M. gypseum. Between the studies, the wide variability of experimental conditions in vitro and ex vivo was observed. The data suggest the need for methodological standardization (at some minimum). This review systematically presents current studies involving agents that present antibiofilm activity against dermatophytes; and an overview of the ideal in vitro and ex vivo experimental conditions to guarantee biofilm formation that may assist future research.

LAY ABSTRACT

This review presents the current studies on the antibiofilm activities of drugs against dermatophytes and ideal experimental conditions, which might guarantee in vitro and ex vivo biofilm formation. It can be useful to examine the efficacy of new antimicrobial drugs against dermatophytes.

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.

Chemical Peeling as an Innovative Treatment Alternative to Oral Antifungals for Onychomycosis in Special Circumstances

Toe nail onychomycosis (ONM) is a common problem in elderly patients. Treatment in diabetic patients with associated comorbidities such as congestive heart failure becomes a challenge. Oral antifungals are best avoided owing to most of them being contraindicated or unsafe due to comorbidities and/or risk of drug interactions stemming from polypharmacy. Topical agents alone are not effective. Unlike isolated ONM in healthy and younger patients, ONM involving multiple nails in geriatric and diabetic patients warrants treatment as it serves as a source of recurrent tinea of the feet and other sites, and even contributes to formation of diabetic foot ulcers. Long-pulsed Nd:YAG and fractional CO>sub<2>/sub< laser (in addition to antifungals) have been reported to provide gratifying results in toe nail ONM. But high treatment cost is a major limitation. Nail peeling with glycolic acid (GA) and low-concentration croton-oil free phenol (CFP) peels have been used in different nail conditions but not specifically for ONM. We report the successful use of Black peel (a superficial-to-medium depth peel used typically for anti-acne and cosmetic indications), a combination of 50% black acetic acid, 0.5% salicylic acid, 6% tetrahydrojasmonic acid, 10% bio sulphur, and 0.1% potassium iodide, in two difficult cases with ONM of multiple nails, the rationale of use being the additional anti-fungal effects of all the peel components.

Evidence for biofilms in onychomycosis

Onychomycosis is a difficult to treat fungal infection of the nails. The chronic nature of onychomycosis contributes to high recurrence rates and the difficulty in treating both dermatophyte and non-dermatophyte infections. It has been hypothesized that the formation of biofilms, sessile, multicellular communities of fungi surrounded by a protective extracellular matrix, allow for fungi to evade current antifungal therapies and contribute to observed antifungal resistance. This review presents the experimental evidence that has accumulated in recent years implicating biofilms in the pathogenesis of onychomycosis. Dermatophytes, non-dermatophyte molds, and yeasts form biofilms in vitro and a model using ex vivo healthy nail fragments has demonstrated biofilm formation on nails for dermatophyte, Candida, and Fusarium species. Implications for disease management are discussed with further research required to incorporate biofilm formation into future drug/device evaluation and treatment protocols.