Methylene blue-mediated photodynamic therapy may be superior to 5% amorolfine nail lacquer for non-dermatophyte onychomycosis

One-pot synthesis and covalent conjugation of methylene blue in mesoporous silica nanoparticles - A platform for enhanced photodynamic therapy

Photodynamic therapy (PDT) is an emerging clinical modality for diverse disease conditions, including cancer. This technique involves, the generation of cytotoxic reactive oxygen species by a photosensitizer in the presence of light and oxygen. Methylene blue (MB) is a cationic dye with an ability to act as photosensitizing and bioimaging agent. The direct utilization of MB as photosensitizer for biological applications has often been impeded by its poor photostability and unwanted tissue interactions. Nanocarriers such as mesoporous silica nanoparticles (MSNs) provide an effective means of overcoming these limitations. However, the mere physical adsorption of the dye within the MSN can result in leakage, compromising the effectiveness of PDT. Therefore, in this work, we report the conjugation of MB into MSNs using novel MB-silane derivatives, namely MBS1 and MBS2, to create dye-doped and amine-functionalized MSNs (MBS1-AMSN and MBS2-AMSN). The PDT efficacy and bioimaging capability of these nanoparticles were compared with those of MSNs in which MB was non-covalently encapsulated (MB@AMSN). The synthesized nanoparticles, ultra-small in size (≤ 35 ± 4 nm) with monodispersity, exhibited enhanced fluorescence quantum yields. MBS1-AMSN demonstrated 70-fold increase, while MBS2-AMSN showed 33-fold improvement in fluorescence quantum yields compared to MB@AMSN at the same concentration. Covalent conjugation resulted in a 2-fold enhancement in the singlet oxygen quantum yield of the dye in MBS1-AMSN and 1.2-fold improvement in MBS2-AMSN, compared to non-covalent encapsulation. Assessment on RAW 264.7 macrophages revealed superior fluorescence in cell imaging for MBS1-AMSN, establishing it as a more efficient PDT agent compared to MBS2-AMSN and MB@AMSN. These findings suggest that MBS1-AMSN holds significant potential as a theranostic nanoplatform for image-guided PDT.

Medium-term antifungal effects of methylene blue versus flavin mononucleotide in the treatment of moderate toenail onychomycosis

BACKGROUND

Methylene blue (MB) and flavin mononucleotide (FMN)-mediated photodynamic therapy (PDT) have demonstrated local antimicrobial effect, but no direct comparative study has been published so far for the treatment of toenail onychomycosis.

OBJECTIVES

To directly compare the short and medium-term efficacy of MB versus FMN as photosensitizers in PDT for toenail onychomycosis by applying them in a 40% w/w urea cream in two different dye concentrations.

METHODS

Forty toenails with distal and lateral subungual moderate onychomycosis due to dermatophyte fungi were randomised to receive 10 weekly sessions of PDT mediated by four topical formulations including MB or FMN at two different concentrations: Group I: 0.1% w/w MB; Group II: 2% w/w MB; Group III: 0.1% w/w FMN; and Group IV: 2% w/w FMN. Photographs were used for onychomycosis severity index (OSI) estimation allowing clinical assessment at any point of the study. Microscopic and microbiological evaluations were carried out at baseline, 27- and 35-week follow-ups. Side effects were recorded along with patient satisfaction.

RESULTS

At week 27, mycological cure rates were 60%, 30%, 50% and 40% and complete cure rates were 0%, 20%, 10% and 20%, for Groups I, II, III and IV respectively. At week 35, mycological cure rates were 70%, 70%, 70% and 60% and complete cure rates were 30%, 50%, 70% and 30%, for Groups I, II, III and IV respectively. All cream formulations were safe and patients were fairly satisfied.

CONCLUSIONS

Results of the present work confirm PDT as a therapeutic alternative for onychomycosis. Although all cream formulations were safe and effective, with a good degree of satisfaction, higher cure rates were obtained with 2% w/w MB cream and 0.1% w/w FMN cream.

Onychomycosis due to Fusarium species in different continents, literature review on diagnosis and treatment

Fusarium species are an emerging cause of onychomycosis, and the number of cases has dramatically increased in recent decades worldwide. This review presents an overview of the onychomycosis cases caused by Fusarium species and diagnosis and treatment that have been reported in the literature. The most common causative agent of onychomycosis is F. solani species complex, which accounts for 11.68% of the cases of Fusarium onychomycosis, followed by the F. oxysporum species complex (164 out of 1669), which is accounted for 9.83% of the total. F. fujikuroi species complex (42 out of 1669) and F. dimerum species complex (7 out of 1669) are responsible for 2.52% and 0.42 cases, respectively. Fusarium nail infections were reported in patients aged range 1-98, accounting for 5.55% (1669 out of 30082) of all cases. Asia has the highest species diversity of Fusarium onychomycosis (31.51%). South America accounts for 21.09%, and the most common causative agent is F. solani (19.32%), followed by F. oxysporum species complex (15.63%). Europe accounts for 4.90% of cases caused by F. oxysporum, followed by F. solani. Africa accounts for 23.87% of the cases due to the F. solani species complex, followed by F. oxysporum and F. fujikuroi. Distal and lateral subungual onychomycosis was the most common clinical symptom accounting for 58.7% (135 out of 230) of the cases. Data analysis relieved that terbinafine and itraconazole are active treatments for Fusarium onychomycosis. For a definitive diagnosis, combining of direct examination, culture and sequencing of the elongation factor of translation 1α are recommended. Accurate identification of the causative agents of onychomycosis due to Fusarium species and antifungal susceptibility testing is essential in patient management.

High Diversity of Fusarium Species in Onychomycosis: Clinical Presentations, Molecular Identification, and Antifungal Susceptibility

Fusarium are uncommon but important pathogenic organisms; they cause non-dermatophyte mould (NDM) onychomycosis. Patients typically respond poorly to treatment owing to Fusarium's native resistance to multiple antifungal drugs. However, epidemiological data for Fusarium onychomycosis are lacking in Taiwan. We retrospectively reviewed the data of 84 patients with positive Fusarium nail sample cultures at Chang Gung Memorial Hospital, Linkou Branch between 2014 and 2020. We aimed to investigate the clinical presentations, microscopic and pathological characteristics, antifungal susceptibility, and species diversity of Fusarium in patients with Fusarium onychomycosis. We enrolled 29 patients using the six-parameter criteria for NDM onychomycosis to determine the clinical significance of Fusarium in these patients. All isolates were subjected to species identification by sequences and molecular phylogeny. A total of 47 Fusarium strains belonging to 13 species in four different Fusarium species complexes (with Fusarium keratoplasticum predominating) were isolated from 29 patients. Six types of histopathology findings were specific to Fusarium onychomycosis, which may be useful for differentiating dermatophytes from NDMs. The results of drug susceptibility testing showed high variation among species complexes, and efinaconazole, lanoconazole, and luliconazole showed excellent in vitro activity for the most part. This study's primary limitation was its single-centre retrospective design. Our study showed a high diversity of Fusarium species in diseased nails. Fusarium onychomycosis has clinical and pathological features distinct from those of dermatophyte onychomycosis. Thus, careful diagnosis and proper pathogen identification are essential in the management of NDM onychomycosis caused by Fusarium sp.

Treatment of Superficial Mycoses Using Photodynamic Therapy: A Systematic Review and Meta-Analysis

Objective: The purpose of this study is to evaluate the effectiveness and safety of photodynamic therapy (PDT) in treating superficial fungal infections, and provide reference for clinical application. Methods: In accordance with Population, Intervention, Comparator, and Outcome (PICO), the research question and keywords were formulated. Records published in English by PubMed, Embase, Cochrane Library, and Web of Science as of November 14, 2022 were retrieved, including the keywords "mycoses," "tinea," "photochemotherapy," etc. Besides, meta-analysis performed by STATA and PROSPERO registration code was CRD42022363448. Results: One thousand four hundred eighty-four records were identified and 18 articles involving 343 patients with superficial fungal infections were enrolled. The overall mycological cure rate of PDT is 55% [95% confidence interval (CI): 0.46-0.65]. The fungal cure rate using methylene blue (MB) as photosensitizer (PS) is 67% (95% CI: 0.55-0.79); using 5-aminolevulinic acid is 34% (95% CI: 0.21-0.47); and using methyl aminolevulinate is 56% (95% CI: 0.33-0.78). The fungal cure rate of moderate-to-severe onychomycosis according to Onychomycosis Severity Index is 60% (95% CI: 0.47-0.73) and that of moderate onychomycosis is 66% (95% CI: 0.56-0.76). It was observed that the treatment parameters did not follow the same standard across studies. The majority of the included studies were moderate to low biased. Conclusions: PDT, particularly using MB as PS, has a certain mycological cure rate and safety at treating superficial mycoses. Due to the insufficient number of studies on PDT in the treatment of superficial fungal infections and the small sample size of some studies, more studies with standardized PDT parameters, large sample size, and long follow-up periods are needed to prove that PDT has the potential to become an alternative to traditional antifungal therapy or to find a better combination between them.

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.

Methylene Blue-Mediated Antimicrobial ​Photodynamic Therapy Against Clinical Isolates of Extensively Drug Resistant ​Gram-Negative Bacteria Causing Nosocomial Infections in Thailand, An In Vitro Study

BACKGROUND/PURPOSE

Some multidrug-resistant gram-negative bacteria as a global threat have been recently prioritized for research and development of new treatments. We studied the efficacy of methylene blue-mediated antimicrobial photodynamic therapy (MB-aPDT) for the reduction of extensively drug-resistant Acinetobacter baumannii (XDR-AB) and Pseudomonas aeruginosa (XDR-PS) and multidrug-resistant Klebsiella pneumoniae (MDR-KP) isolated in a university hospital setting in Thailand.

METHOD

Two isolates of each selected bacterium were collected, XDR-AB1 and AB2, XDR- PS1 and PS2, and MDR-KP1 and KP2. Three triplicate experiments using various MB concentrations alone, various red light fluences alone, as well as the selected non-toxic doses of MB and fluences of red light combined as MB-aPDT were applied on each selected isolate. The colonies were counted [colony forming units (CFU)/ml]. Estimation of the lethal treatment dose defined as reduction of > 2 log₁₀ in CFU/ml compared with untreated bacteria.

RESULT

There were generally negligible changes in the viable counts of the bacterial suspensions treated with all the MB concentrations (p > 0.05). In the second experiment with the only red light treatments, at fluences higher than 2 J/cm, reduction trend in viable counts across all the isolates was observed. Only for MDR-KP1, however, the lethal dose was achieved with the highest fluence of red light (80 J/cm). With the concentration of MB, 50 and 150 mg/L in the third experiment (MB-aPDT), the greater bacterial reduction was observed in all clinical isolates leading to their lethal viable cell reduction when escalating the light fluence to 80 J/cm.

CONCLUSIONS

MB-aPDT evidently killed the selected XDR and MDR-gram negative bacteria. In highly drug-resistant crisis era, MB-aPDT could be a promising option, particularly for local infections and infection complicating chronic wounds.