Utilidad de la terapia fotodinámica en el manejo de la onicomicosis

Fractional CO2 laser - assisted methylene blue photodynamic therapy is a potential alternative therapy for onychomycosis in the era of antifungal resistance

BACKGROUND

Treatment of onychomycosis is challenging by virtue of the impact of nail disfigurement, the location of the fungi within the nail and reported antifungal resistance worldwide. Light-based technologies are promising primary or adjunctive therapeutic modalities. We aimed to compare the efficacy of photodynamic therapy and fractional CO2 laser monotherapy either alone or in combination for onychomycosis.

PATIENTS AND METHODS

This prospective randomized comparative study was conducted on 51 onychomycosis patients divided into three groups. In group A, patients were treated using 6 photodynamic therapy sessions using methylene blue and IPL (560 to 700 nm, fluence 12 J/cm2). Group B patients were treated using 6 bimonthly fractional CO2 laser sessions (10,600 nm, 1.600 mj energy and 0.6 mm density) and group C patients were treated using 6 combined fractional CO2 laser and photodynamic therapy sessions. Patients were evaluated mycologically, dermoscopically and clinically by calculation of proximal nail diameter percentage at baseline, monthly, at the end of treatment and after a 6-month follow-up period post-treatment.

RESULTS

Candida was the most commonly isolated organismin in 64.7%, 70.6% and 70.6% of the pateints in groups A, B and C, respectively. The dermoscopic findings in the total dystrophic onychomycosis was subungual hyperkeratosis in 6 patients (100%), longitudinal streaks and striae in 1 patient (16.7%). In dorsolateral subungual onychomycosis, jagged proximal edge in 31 patients (70.5%), and pigmentation in 30 patients (68.2%) were noted. In proximal subungual onychomycosis irregular matt patches were seen in 1 patient (100%). Proximal nail diameter percentage showed statistically significant improvement after treatment and 6 months follow up in the 3 studied groups. Mean increase of proximal nail diameter after treatment was highest in group C (52.94 ± 20.24), followed by group B (43.82 ± 21.03) and least in group A (35.29 ± 17.0). This difference was statistically significant (p = 0.044). Reported side effects were mild-moderate pain, discoloration and paronychia.

CONCLUSION

We conclude that fractional CO2 laser and photodynamic monotherapy, and their combination achieve high success rates, good patient satisfaction and safety profile. Fractional CO2-assisted photodynamic therapy is associated with the highest improvement over either fractional CO2 or photodynamic therapy alone.

Onychomycosis in Patients with Diabetes Mellitus in Africa: A Global Scoping Review, 2000-2021

Onychomycosis is commonly studied in Africa but not in patients with diabetics despite having a significant number of her population living with diabetes mellitus (DM). Our review highlights a total of 15 studies with only two from Africa over the past two decades; 8 (53.3%) from Asia, 4 (26.7%) from Europe, 2 (13.3%) from Africa and 1 (6.7%) from North America. A total number of 4321 participants were involved with onychomycosis prevalence of 35.3% (1527/4321). Seven studies documented preponderance of onychomycosis in males, one showed preponderance in females, one showed no statistically significant difference in gender, while correlation with gender was unclear in the remainder. The risk factors identified were duration of diabetes, increasing age, occupation (agriculture), subclinical atherosclerosis, metabolic syndrome, obesity, triglyceride levels, and glycosylated haemoglobin. Three case control studies showed a statistically significant correlation between onychomycosis and individuals with DM. Diagnosis was mainly by microscopy and culture with Trichophyton (T) rubrum as the predominant isolate. Fungal nail infections are grossly underdiagnosed and/or underreported in Africa and hence the need for improved awareness and diagnosis especially in patients with DM. Although focused on Africa, this study also revealed paucity of data on onychomycosis in diabetic patients living in the Americas despite evidence from the literature showing a significant number of individuals from that region are living with diabetes. The need to evaluate this at-risk population for onychomycosis cannot be over emphasized.

Response surface methodological approach for optimization of photodynamic therapy of onychomycosis using chlorin e6 loaded nail penetration enhancer vesicles

Antimicrobial photodynamic inactivation (aPDI) has a tremendous potential as an alternative therapeutic modality to conventional antifungals in treatment of onychomycosis, yet the nail barrier properties and the deep-seated nature of fungi within the nails remain challenging. Therefore, the aim of this study was to prepare, optimize, and characterize Chorin e6 (Ce6) nail penetration enhancer containing vesicles (Ce6-nPEVs) and evaluate their photodynamic mediated effect against Trichophyton rubrum (T.rubrum); the main causative agent of onychomycosis. Optimization of the particle size and encapsulation efficiency of nPEVs was performed using a four-factor two-level full factorial design. The transungual delivery potential of the selected formulation was assessed in comparison with the free drug. The photodynamic treatment conditions for T.rubrum aPDI by free Ce6 was optimized using response surface methodology based on Box-Behnken design, and the aPDI effect of the selected Ce6-nPEVs was evaluated versus the free Ce6 at the optimized condition. Results showed that formulations exhibited high encapsulation efficiency for Ce6 ranging from 79.4 to 98%, particle sizes ranging from 225 to 859 nm, positive zeta potential values ranging from +30 to +70 mV, and viscosity ranging from 1.26 to 3.43 cP. The predominant parameters for maximizing the encapsulation efficiency and minimizing the particle size of Ce6-nPEVs were identified. The selected formulation showed 1.8-folds higher nail hydration and 2.3 folds improvement in percentage of Ce6 up-taken by nails compared to the free drug. Results of the microbiological study confirmed the reliability and adequacy of the Box-Behnken model, and delineated Ce6 concentration and incubation time as the significant model terms. Free Ce6 and Ce6-nPEVs showed an equipotent in vitro fungicidal effect on T.rubrum at the optimized conditions, however Ce6-nPEVs is expected to show a differential effect at the in vivo level where the advantage of the enhanced nail penetration feature will be demonstrated.

Combination of Photodynamic Therapy and Oral Antifungals for the Treatment of Onychomycosis

Onychomycosis accounts for 50% of nail disorders, making it one of the most prevalent fungal diseases and a therapeutic challenge. Photodynamic therapy (PDT) could constitute a therapeutic alternative, owing to its good adherence, the low probability of resistance, the lack of interaction with antimicrobials, and its favorable adverse effect profile. This retrospective observational study included all patients with a microbiological diagnosis of onychomycosis treated with PDT at Miguel Servet University Hospital, Zaragoza (Spain), between January 2013 and June 2021. The protocol consisted of pre-treatment with 40% urea for 7 days, followed by 16% methyl-aminolevulinate (MAL) for 3 h and subsequent irradiation with a red-light LED lamp (37 J/cm²), every 1 or 2 weeks. Combined treatment with oral and/or topical antifungals was recorded. Of the 20 patients included (mean age, 59 ± 17 years), 55% were men. The most frequently detected microorganism was Trichophyton rubrum (55%). The most commonly affected location was the feet (90%): 50% of these cases were associated with tinea pedis. The median (standard deviation) number of PDT sessions was 6 (2.8). PDT was combined with systemic terbinafine (250 mg/day) in 10 cases (in 8 cases, this was administered for only 1 month), and with topical terbinafine in 3 cases. A complete clinical response was achieved in 80% (16) of cases and microbiological cure in 60% (12). PDT is a therapeutic alternative for onychomycosis, and can be administered either in monotherapy or combined with antifungals, allowing for a reduction in the duration and possible adverse effects of antifungal treatment and achieving higher cure rates than those obtained with either treatment alone.

Photosensitizers Mediated Photodynamic Inactivation against Fungi

Superficial and systemic fungal infections are essential problems for the modern health care system. One of the challenges is the growing resistance of fungi to classic antifungals and the constantly increasing cost of therapy. These factors force the scientific world to intensify the search for alternative and more effective methods of treatment. This paper presents an overview of new fungal inactivation methods using Photodynamic Antimicrobial Chemotherapy (PACT). The results of research on compounds from the groups of phenothiazines, xanthanes, porphyrins, chlorins, porphyrazines, and phthalocyanines are presented. An intensive search for a photosensitizer with excellent properties is currently underway. The formulation based on the existing ones is also developed by combining them with nanoparticles and common antifungal therapy. Numerous studies indicate that fungi do not form any specific defense mechanism against PACT, which deems it a promising therapeutic alternative.

Methylene blue vs methyl aminolevulinate photodynamic therapy in combination with oral terbinafine in the treatment of severe dermatophytic toenail onychomycosis: Short- and long-term effects

BACKGROUND

Photodynamic therapy (PDT) kills target microorganisms via reactive oxygen species (ROS) production. PDT seems to be a good alternative treatment option for onychomycosis.

OBJECTIVE

To compare the efficacy of combined therapies based on oral terbinafine (TN) plus adjunctive PDT mediated by methylene blue (MB) (TN + MB/PDT) or methyl aminolevulinate (MAL) (TN + MAL/PDT) in the treatment of onychomycosis.

METHODS

Twenty patients affected by severe dermatophyte onychomycosis in the nails of the big toe (>60% disease involvement of target nail) received oral TN for 12 weeks and concomitantly were randomly allocated to receive nine sessions, separated by 2-week intervals, of urea (40%) plus a PDT protocol mediated by MB (TN + MB/PDT: group I) or mediated by MAL (TN + MAL/PDT: group II). Clinical and mycological efficacy was evaluated at 16-, 40- and 52-week follow-up.

RESULTS

Both protocols showed a significant decrease in Onychomycosis Severity Index (OSI) scores (P < .05), from 24.2 ± 4.6 to 0.7 ± 0.6 (group I)) and from 18.5 ± 10.1 to 2.1 ± 2.0 (group II). No side effects or complications were reported in any of the combinations used. Mycological cure rates were significantly higher during the last third of the evaluated period of time, reaching 100% and 90% in group I and group II, respectively, at the 52-week follow-up. In both modalities, complete cure was achieved in 70% of the patients at the 52-week follow-up.

CONCLUSIONS

TN + MB/PDT and TN + MAL/PDT show similar outcomes in the treatment of toenails with severe onychomycosis. PDT is an effective method to accelerate the TN-mediated healing process.

Effect of Nail Thickness on Visible Radiation Transmittance: Implications for New Photodynamic Therapy Technologies in Onychomycosis

Photodynamic therapy is taking importance as a nonintrusive treatment for nail onychomycosis. Knowledge of true transmittance values across nails could lead to qualitative and quantitative improvements in light-based treatments. We have characterized the spectral transmittance of healthy and fungally infected human fingernails and toenails according to nail thickness, and we propose a surface transmittance model for the small-scale optimization of light-based treatments. Transmittance of fingernails and toenails was analyzed by means of spectroradiometric measurements under solar-simulated visible light radiation (400 nm to 750 nm). The nail thickness was measured by means of microscope measurement. Transmittance was highest at longer wavelengths and decreased gradually as the wavelengths became shorter but with a significant nail transmittance of around 20% in the blue region of the spectrum. In the case of nails affected by onychomycosis, transmittance fell to under 10% because of the thickness of the nails, with no changes in spectral characteristics of transmitted light. Nail thickness is the main variable controlling exponentially light transmission in the visible spectrum and not only red radiation is effective for nail onychomycosis PDT. Blue light, the spectral band more effective for PPIX absorption is also effectively transmitted.

Employment of methylene blue irradiated with laser light source in photodynamic inactivation of biofilm formed by Candida albicans strain resistant to fluconazole

A promising approach for the eradication of biofilm formed by the yeast Candida albicans seems to be photodynamic inactivation (PDI). This work presents a use of methylene blue (MB, 1 mM) irradiated with a red laser (output power 190 mW/cm2, wavelength 660 nm) for the eradication of a biofilm formed by the fluconazole-resistant (FLC-resistant) strain C. albicans CY 1123 compared to the standard strain C. albicans SC5314. The periods of irradiation corresponded to the fluence of 15, 23 and 57 J/cm2. Effectiveness of PDI was evident with following percentage of survived biofilm cells: 24.57, 23.46, and 22.29% for SC5314 and 40.28, 17.91, and 5.89% for CY 1123, respectively, compared to the samples without irradiation. Light and confocal laser scanning microscopy confirmed the effectiveness of PDI. However, the morphological form of C. albicans seems to play an important role as well, since prolonged duration of irradiation did not increase efficiency of PDI on C. albicans SC5314. An experiment with the yeast-to-hyphae transition revealed that the FLC-resistant strain expressed a markedly reduced capacity to form hyphae compared to SC5314. We summarized that PDI was effective on biofilm formed by the FLC-resistant strain, but resistance most likely did not play significant role in PDI. Additionally, we observed differences in susceptibility to PDI between biofilms composed of the mycelia and only of the yeasts, and finally, the employment of a laser in PDI enabled a decreasing period of irradiation while maintaining the high effectiveness of PDI.

In vitro antifungal activity of organic compounds derived from amino alcohols against onychomycosis

Onychomycosis is a fungal infection of the nail caused by high densities of filamentous fungi and yeasts. Treatment for this illness is long-term, and recurrences are frequently detected. This study evaluated in vitro antifungal activities of 12 organic compounds derived from amino alcohols against standard fungal strains, such as Trichophyton rubrum CCT 5507 URM 1666, Trichophyton mentagrophytes ATCC 11481, and Candida albicans ATCC 10231. The antifungal compounds were synthesized from p-hydroxybenzaldehyde (4a–4f) and p-hydroxybenzoic acid (9a–9f). Minimum inhibitory concentrations and minimum fungicidal concentrations were determined according to Clinical and Laboratory Standards Institute protocols M38-A2, M27-A3, and M27-S4. The amine series 4b–4e, mainly 4c and 4e compounds, were effective against filamentous fungi and yeast (MIC from 7.8 to 312 μg/mL). On the other hand, the amide series (9a–9f) did not present inhibitory effect against fungi, except amide 9c, which demonstrated activity only against C. albicans. This allowed us to infer that the presence of amine group and intermediate carbon number (8C–11C) in its aliphatic side chain seems to be important for antifungal activity. Although these compounds present cytotoxic activity on macrophages J774, our results suggest that these aromatic compounds might constitute potential as leader molecules in the development of more effective and less toxic analogs that could have considerable implications for future therapies of onychomycosis.

Photodynamic Therapy and Skin Appendage Disorders: A Review

Photodynamic therapy (PDT) is a noninvasive treatment that utilizes light treatment along with application of a photosensitizing agent. In dermatology, PDT is commonly used and approved for the treatment of oncological conditions such as actinic keratosis, Bowen disease and superficial basal cell carcinoma. In the last 2 decades however, PDT has also been used for the treatment of several nonneoplastic dermatological diseases. The present review summarizes published data on PDT application in skin appendage disorders. Our literature review shows that: (a) PDT may be a suitable treatment for acne, folliculitis decalvans, hidradenitis suppurativa, nail diseases, and sebaceous hyperplasia; (b) there is a lack of agreement on PDT features (type, concentrations and incubation period of used substances, number and frequency of PDT sessions, optimal parameters of light sources, and patient characteristics [e.g., failure to previous treatments, disease severity, body surface area involved, etc.] which should guide PDT use in these diseases);