Antimicrobial photodynamic therapy for oral Candida infection in adult AIDS patients: A pilot clinical trial

The Light-activated Effect of Natural Anthraquinone Parietin against Candida auris and Other Fungal Priority Pathogens

Antimicrobial photodynamic therapy (aPDT) is an evolving treatment strategy against human pathogenic microbes such as the Candida species, including the emerging pathogen C. auris. Using a modified EUCAST protocol, the light-enhanced antifungal activity of the natural compound parietin was explored. The photoactivity was evaluated against three separate strains of five yeasts, and its molecular mode of action was analysed via several techniques, i.e., cellular uptake, reactive electrophilic species (RES), and singlet oxygen yield. Under experimental conditions (λ = 428 nm, H = 30 J/cm2, PI = 30 min), microbial growth was inhibited by more than 90% at parietin concentrations as low as c = 0.156 mg/L (0.55 µM) for C. tropicalis and Cryptococcus neoformans, c = 0.313 mg/L (1.10 µM) for C. auris, c = 0.625 mg/L (2.20 µM) for C. glabrata, and c = 1.250 mg/L (4.40 µM) for C. albicans. Mode-of-action analysis demonstrated fungicidal activity. Parietin targets the cell membrane and induces cell death via ROS-mediated lipid peroxidation after light irradiation. In summary, parietin exhibits light-enhanced fungicidal activity against all Candida species tested (including C. auris) and Cryptococcus neoformans, covering three of the four critical threats on the WHO's most recent fungal priority list.

Comparative effectiveness of interventions for the treatment of peri-implantitis: A systematic review with network meta-analysis

STATEMENT OF PROBLEM

Extensive research has been carried out on the various aspects of diagnosing and treating peri-implantitis. However, clinical guidelines for the management of peri-implantitis based on high quality evidence are lacking.

PURPOSE

The purpose of this systematic review with network meta-analysis was to analyze the current evidence on nonsurgical and surgical interventions for the treatment of peri-implantitis and synthesize clinical guidelines based on high quality evidence.

MATERIAL AND METHODS

A search was conducted for trials published in Medline, Scopus, PubMed, and Cochrane Central Register of Controlled Trials from inception until July 2023. The study was registered with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023451056). A network meta-analysis was performed on data from randomized controlled trials that assessed nonsurgical and surgical interventions for the treatment of peri-implantitis. The interventions were ranked according to their efficacy using surface under the cumulative ranking (SUCRA) system. The grading of recommendations, assessment, development, and evaluations (GRADE) approach was used to assess the level of certainty of evidence.

RESULTS

A total of 45 articles were included in the quantitative analysis. The GRADE approach determined a moderate to high level of certainty of evidence. Among the nonsurgical interventions, mechanical debridement with adjunctive systemic antibiotics was significant in improving probing depth at 3 months and beyond 6 months, clinical attachment loss at 3 months, and clinical attachment loss beyond 6 months. Mechanical debridement with adjunctive topical antibiotics was significant in improving probing depth beyond 6 months, clinical attachment loss at 3 months, clinical attachment loss beyond 6 months, and radiographic bone loss beyond 6 months. Mechanical debridement with adjunctive photodynamic therapy was significant in improving probing depth beyond 6 months, clinical attachment loss at 3 months, clinical attachment loss beyond 6 months, and radiographic bone loss beyond 6 months. Mechanical debridement with adjunctive systemic antibiotics and photodynamic therapy was significant in improving probing depth beyond 6 months. Among surgical interventions, open flap debridement with implant surface decontamination and open flap debridement with decontamination and adjunctive photodynamic therapy were significant in improving probing depth at 3 months.

CONCLUSIONS

Mechanical debridement with adjunctive systemic antibiotics or photodynamic therapy results in improved clinical outcomes.

Impact of PVC microplastics in photodynamic inactivation of Staphylococcus aureus and MRSA

Photodynamic processes have found widespread application in therapies. These processes involve photosensitizers (PSs) that, when excited by specific light wavelengths and in the presence of molecular oxygen, generate reactive oxygen species (ROS), that target cells leading to inactivation. Photodynamic action has gained notable attention in environmental applications, particularly against pathogens and antibiotic-resistant bacteria (ARB) that pose a significant challenge to public health. However, environmental matrices frequently encompass additional contaminants and interferents, including microplastics (MPs), which are pollutants of current concern. Their presence in water and effluents has been extensively documented, highlighting their impact on conventional treatment methods, but this information remains scarce in the context of photodynamic inactivation (PDI) setups. Here, we described the effects of polyvinyl chloride (PVC) microparticles in PDI targeting Staphylococcus aureus and its methicillin-resistant strain (MRSA), using curcumin as a PS under blue light. The presence of PVC microparticles does not hinder ROS formation; however, depending on its concentration, it can impact bacterial inactivation. Our results underscore that PDI remains a potent method for reducing bacterial concentrations in water and wastewater containing ARB, even in highly contaminated scenarios with MPs.

Photodynamic therapy in the coadjuvant treatment of Sporothrix schenckii complex

INTRODUCTION

Sporotrichosis, a zoonosis caused by animal, mainly cat, scratches or bites, is caused by fungi belonging to the Sporothrix complex. Treatment usually consists in antifungal administration, although treatment failure and hepatotoxicity reports have been noted. Alternative sporotrichosis treatment methods, such as antimicrobial photodynamic therapy (aPDT), may, therefore, be indicated.

CASE REPORT

In this context, this study followed a 56-year-old male renal transplanted patient displaying disseminated sporotrichosis, presenting erythematous skin lesions with ulcerated backgrounds and hardened consistency on the nose, oral and scalp. The lesions were present for about 2 months and the patient coexisted with cats. Intravenous amphotericin B administration was initiated, and immunosuppression was suspended. Seven aPDT sessions were also performed in 48 h intervals on the oral lesions, employing 0.01% methylene blue gel as the photosensitizing agent. After the 4th aPDT session, the patient was discharged, amphotericin B administration was suspended, and the treatment was continued with itraconazole, without immunosuppression. Red laser was applied to the oral lesions after the 7th aPDT session. Significant lesion improvement was observed after the final aPDT session and complete palate lesion repair was noted after two red laser sessions.

CONCLUSION

These findings indicate that aPDT is a valuable strategy as an adjunct sporotrichosis treatment.

A Uniform Design Method Can Optimize the Combinatorial Parameters of Antimicrobial Photodynamic Therapy, Including the Concentrations of Methylene Blue and Potassium Iodide, Light Dose, and Methylene Blue's Incubation Time, to Improve Fungicidal Effects on Candida Species

The optimal combinatorial parameters of antimicrobial photodynamic therapy (aPDT) mediated by methylene blue (MB) with the addition of potassium iodide (KI) against Candida species have never been defined. This study aimed to optimize the combinatorial parameters of aPDT, including the concentrations of MB (X1, 0.1-1.0 mM) and KI (X2, 100-400 mM), light dose (X3, 10-70 J/cm2), and MB's incubation time (X4, 5-35 min) for three Candida species. The best MB + KI-aPDT fungicidal effects (Y) against Candida albicans ATCC 90028 (YCa), Candida parapsilosis ATCC 22019 (YCp), and Candida glabrata ATCC 2950 (YCg) were investigated using a uniform design method. The regression models deduced using this method were YCa = 7.126 + 1.199X1X3 - 1.742X12 + 0.206X22 - 0.361X32; YCp = 10.724 - 0.867X1 - 1.497X2 + 0.560X3 + 1.298X22; and YCg = 0.892 - 0.956X1 + 2.296X3 + 1.299X42 - 3.316X3X4. The optimal combinatorial parameters inferred from the regression equations were MB 0.1 mM, KI 400 mM, a light dose of 20 J/cm2, and a 5-minute incubation time of MB for Candida albicans; MB 0.1 mM, KI 400 mM, a light dose of 70 J/cm2, and a 5-minute incubation time of MB for Candida parapsilosis; MB 0.1 mM, KI 100 mM, a light dose of 10 J/cm2, and a 35-minute incubation time of MB for Candida glabrata. The uniform design method can optimize the combinatorial parameters of aPDT mediated by MB plus KI to obtain the best aPDT fungicidal effects on Candida species, providing a new method to optimize the combinatorial parameters of aPDT for different pathogens in the future.

Phenylalanine-Arginine-β-Naphthylamide Enhances the Photobactericidal Effect of Methylene Blue on Pseudomonas aeruginosa

Objective: To investigate the effectiveness, dosing sequence, concentration, and mechanism of antimicrobial photodynamic inactivation (aPDI) using methylene blue (MB) plus phenylalanine-arginine-β-naphthylamide (PAβN) against Pseudomonas aeruginosa. Methods: P. aeruginosa bacterial suspension was incubated with MB for different times (5-240 min), and then, 10 J/cm2 red light was irradiated. The efflux pump inhibitor (EPI) PAβN (10-100 μg/mL) was combined with MB (1-20 μM) in different sequences (PAβN-first, PAβN+MB, PAβN-after). Colony-forming units were then determined by serial dilution. Results: Using MB 10 μM plus 10 J/cm2, the killing effect of MB-aPDI on P. aeruginosa increased first and then decreased with longer incubation time. The killing effect of MB+PAβN-aPDI on P. aeruginosa was better than that of MB-aPDI (p < 0.05) by up to 2 logs. PAβN-first had the best killing effect, whereas PAβN-after had the worst killing effect. The killing effect increased with PAβN concentration and at 100 μg/mL reached 5.1 logs. Conclusions: The EPI PAβN enhanced the bactericidal effect of MB-aPDI on P. aeruginosa, especially when added before MB. It is proposed that MB is a substrate of the resistance-nodulation-division family efflux pump.

Enhancing Antimicrobial Photodynamic Therapy with Phenothiazinium Dyes and Sodium Dodecyl Sulfate Against Candida Albicans at Various Growth Stages

BACKGROUND

The eradication of C. albicans is difficult due to the organization of the yeast in biofilms. Photodynamic therapy (PDT) has been proposed as an alternative to antifungals. Phenothiazinium dyes, e.g. methylene blue (MB), have been proposed as photosensitizing agents (PS), and their association with sodium dodecyl sulfate (SDS) has recently been shown to improve the effectiveness of PDT in planktonic culture. In this sense, the objective of this work was to evaluate the effect of PDT with phenothiazinium dyes associated to SDS in biofilms at the different stages of growth.

METHODS

Experiments were carried out to evaluate the effects of PDT on biofilm formation and on established biofilms of C. albicans ATCC 10231. Samples were exposed to PS 50 mg/L (MB, Azure A - AA, Azure B - AB and dimethyl methylene blue - DMMB) dissolved in water or 0.25% SDS, for 5 minutes in the dark. After irradiation at 660 nm, 37.3mW/cm² for 27 minutes, 60.4J/cm² colony forming units count assay (CFU/mL) was performed. One or two irradiations were applied. Statistical methods were used to assess effectiveness.

RESULTS

PSs showed low toxicity in the dark. An application of PDT irradiation was not able to reduce the CFU/mL both in mature biofilms (24h) and in biofilms in the dispersion phase (48h), only in the adherence phase did PDT prevent the formation of biofilms. With two successive applications of PDT irradiation in the dispersion phase, PDT with MB, AA, and DMMB completely inactivated C. albicans. The similar was not observed with mature biofilms.

CONCLUSIONS

Different stages of biofilm growth respond differently to PDT, with the greatest inhibitory effect found in the adhesion stage. Mature and dispersed biofilms are less susceptible to PDT. The use of two successive applications of PDT with PSs associated with SDS may be a useful approach to inactivate C. albicans biofilms.

The combination of methylene blue and sodium dodecyl sulfate enhances the antimicrobial photodynamic therapy of Candida albicans at lower light parameters

BACKGROUND

The growth of resistant microorganisms has been a challenge for health systems. Antimicrobial Photodynamic Therapy (aPDT) has gained attention due to its effects on resistant strains. Recently, it was shown that the association of methylene blue (MB) and sodium dodecyl sulfate (SDS) is an effective strategy to increase the effect of aPDT; however, it is unknown which are the best light parameters (such as irradiance and radiant exposure, RE), to reach the most effective protocols. This work aimed to evaluate the light parameters, irradiance, and radiant exposure, in aPDT with MB when conveyed in water compared to MB associated with SDS.

METHODS

Tests were carried out to quantify the colony-forming units (CFU) of ATCC 10231 strain of Candida albicans when using MB in different media and with different light parameters: Control (water), SDS (0.25%), MB (20 mg/mL), and the MB/SDS at irradiances of 3.7; 11.2; 18.6, and 26.1 mW/cm² and varied irradiation times to reach radiant exposures of 4.4; 17.8; 26.7, and 44 J/cm².

RESULTS

The results showed that aPDT with MB/SDS had a higher antimicrobial effect than MB when conveyed in water. Furthermore, for the highest irradiance studied (26.1 mW/cm²), CFU decreases exponentially with increasing RE from 4.4 up to 44J/cm². Similarly, at a fixed RE, the higher the irradiance used, the higher the antimicrobial effect was observed, except for the lowest RE studied (4.4 J/cm²).

CONCLUSIONS

aPDT with MB/SDS had a greater antimicrobial action at the lower light parameters when compared to MB conveyed in water. The authors suggest the use of RE above 18 J/cm² and irradiance above 26mW/cm² since at the mentioned parameters the increase in its value caused a greater antimicrobial effect.

Short-term influence of antimicrobial photodynamic therapy as an adjuvant to mechanical debridement in reducing soft-tissue inflammation and subgingival yeasts colonization in patients with peri-implant mucositis

OBJECTIVE

The objective of this short-term follow-up study was to evaluate the influence of antimicrobial photodynamic therapy (aPDT) as an adjuvant to mechanical debridement (MD) in reducing soft-tissue inflammation and subgingival yeasts colonization (SYC) in patients with peri‑implant mucositis (PiM).

METHODS

Individuals diagnosed with PiM were included. Demographic data was collected using a questionnaire. Peri-implant plaque index (PI), bleeding index (BI), probing depth (PD), crestal bone levels and SYC were measured at baseline. Therapeutically, these individuals were divided into test and control groups. In the control-group patients underwent MD and in the test-group patients underwent MD with adjunct single session of aPDT. Clinical peri‑implant parameters and SYC were reassessed after 12-weeks. Correlation between age, gender and duration of implants with SYC and clinical peri‑implant status was assessed using logistic regression models. P < 0.05 was selected as an indicator of statistical significance.

RESULTS

The test and control-groups comprised of 24 and 23 individuals, respectively. In the test and control groups, toothbrushing twice daily was reported by 7 (29.2%) and 5 (21.7%) individuals, respectively. None of the individuals had ever used a dental floss. At baseline, there was no difference in peri‑implant PI, BI, PD and CBL in the test and control groups. At follow-up, peri‑implant PI (P < 0.01), BI (P < 0.01) and PD (P < 0.01) were significantly higher in the control compared with the test-group. At baseline, SYC in the test and control groups were 1865.3 ± 403.4 CFU/ml and 1963.7 ± 512.4 CFU/ml, respectively. At 90 days' follow-up, SYC in the test and control groups were 1472 ± 202.7 and 1538.4 ± 331.7 CFU/ml, respectively. There was no significant difference in SYC in both groups when baseline values were compared with 90 days' follow-up.

CONCLUSION

One session of aPDT after MC with adjunct aPDT is effective in reducing soft tissue inflammation but not SYC in patients with PiM.

Clinical applications of antimicrobial photodynamic therapy in dentistry

Given the emergence of resistant bacterial strains and novel microorganisms that globally threaten human life, moving toward new treatment modalities for microbial infections has become a priority more than ever. Antimicrobial photodynamic therapy (aPDT) has been introduced as a promising and non-invasive local and adjuvant treatment in several oral infectious diseases. Its efficacy for elimination of bacterial, fungal, and viral infections and key pathogens such as Streptococcus mutans, Porphyromonas gingivalis, Candida albicans, and Enterococcus faecalis have been investigated by many invitro and clinical studies. Researchers have also investigated methods of increasing the efficacy of such treatment modalities by amazing developments in the production of natural, nano based, and targeted photosensitizers. As clinical studies have an important role in paving the way towards evidence-based applications in oral infection treatment by this method, the current review aimed to provide an overall view of potential clinical applications in this field and summarize the data of available randomized controlled clinical studies conducted on the applications of aPDT in dentistry and investigate its future horizons in the dental practice. Four databases including PubMed (Medline), Web of Science, Scopus and Embase were searched up to September 2022 to retrieve related clinical studies. There are several clinical studies reporting aPDT as an effective adjunctive treatment modality capable of reducing pathogenic bacterial loads in periodontal and peri-implant, and persistent endodontic infections. Clinical evidence also reveals a therapeutic potential for aPDT in prevention and reduction of cariogenic organisms and treatment of infections with fungal or viral origins, however, the number of randomized clinical studies in these groups are much less. Altogether, various photosensitizers have been used and it is still not possible to recommend specific irradiation parameters due to heterogenicity among studies. Reaching effective clinical protocols and parameters of this treatment is difficult and requires further high quality randomized controlled trials focusing on specific PS and irradiation parameters that have shown to have clinical efficacy and are able to reduce pathogenic bacterial loads with sufficient follow-up periods.

Japonamides A and B, Two New Cyclohexadepsipeptides from the Marine-Sponge-Derived Fungus Aspergillus japonicus and Their Synergistic Antifungal Activities

Two new cyclohexadepsipeptides japonamides A (1) and B (2) were isolated from the ethyl acetate extract of a marine-sponge-derived fungus Aspergillus japonicus based on molecular networking. Their structures were elucidated by comprehensive spectral analysis and their absolute configurations were confirmed by Marfey's method. Compounds 1 and 2 showed no antifungal activities against Candida albicans SC5314 measured by the broth microdilution method but exhibited prominent synergistic antifungal activities in combination with fluconazole, ketoconazole, or rapamycin. The Minimum inhibitory concentrations (MICs) of rapamycin, fluconazole, and ketoconazole were significantly decreased from 0.5 to 0.002 μM, from 0.25 to 0.063 μM, and from 0.016 to 0.002 μM, in the presence of compounds 1 or 2 at 3.125 μM, 12.5 μM, and 6.25 μM, respectively. Surprisingly, the combination of compounds 1 or 2 with rapamycin showed a strong synergistic effect, with fractional inhibitory concentration index (FICI) values of 0.03.