Photodynamic topical antimicrobial therapy for infected foot ulcers in patients with diabetes: a randomized, double-blind, placebo-controlled study--the D.A.N.T.E (Diabetic ulcer Antimicrobial New Topical treatment Evaluation) study

A meta-analysis and systematic review of photodynamic therapy for diabetic foot ulcers

BACKGROUND

Diabetic foot ulcer (DFU) is a chronic and challenging condition, addressed through various treatments including photodynamic therapy (PDT) and standard of care (SOC), yet lacking consensus on the optimal approach. This study presents a comprehensive meta-analysis of randomized controlled trials to evaluate the efficacy and safety of PDT versus SOC in managing DFU.

METHODS

An extensive literature search was conducted across PubMed, Embase, and the Cochrane Library databases to identify RCTs that compared the effectiveness of PDT with SOC in treating DFU. The primary metrics evaluated included changes in ulcer area, wound healing indices, and pain levels experienced by the patients.

RESULTS

This meta-analysis incorporated data from 6 RCTs, encompassing 458 patients with 467 DFUs. The analysis indicated that while PDT led to a faster reduction in ulcer size compared to SOC, the difference was not statistically significant [mean difference (MD): 2.73cm², 95 % Confidence Interval (CI) -2.98 to 8.44; p > 0.05]. However, a notable improvement was observed in the wound healing rate in the PDT group [MD: 29.26 %, 95 % CI 7.24 to 51.28; p = 0.01]. Based on the Visual Analog Scale (VAS), pain assessment revealed no significant difference between the two treatment groups [MD: 2.35, 95 % CI -2.36 to 7.06; p = 0.33].

CONCLUSION

The study suggests that PDT might offer an enhanced healing rate for DFUs compared to SOC alone, potentially leading to improved patient outcomes. Importantly, our findings highlight the superiority of photodynamic therapy in accelerating ulcer healing without an associated increase in complications.

PROSPERO

2023 CRD42023493930.

Photodynamic inactivation of E. coli with cationic imidazolyl-porphyrin photosensitizers and their synergic combination with antimicrobial cinnamaldehyde

Bacterial infections are a global health concern, particularly due to the increasing resistance of bacteria to antibiotics. Multi-drug resistance (MDR) is a considerable challenge, and novel approaches are needed to treat bacterial infections. Photodynamic inactivation (PDI) of microorganisms is increasingly recognized as an effective method to inactivate a broad spectrum of bacteria and overcome resistance mechanisms. This study presents the synthesis of a new cationic 5,15-di-imidazolyl porphyrin derivative and the impact of n-octanol/water partition coefficient (logP) values of this class of photosensitizers on PDI efficacy of Escherichia coli. The derivative with logP = -0.5, IP-H-OH2+, achieved a remarkable 3 log CFU reduction of E. coli at 100 nM with only 1.36 J/cm2 light dose at 415 nm, twice as effective as the second-best porphyrin IP-H-Me2+, of logP = -1.35. We relate the rapid uptake of IP-H-OH2+ by E. coli to improved PDI and the very low uptake of a fluorinated derivative, IP-H-CF32+, logP ≈ 1, to its poor performance. Combination of PDI with cinnamaldehyde, a major component of the cinnamon plant known to alter bacteria cell membranes, offered synergic inactivation of E. coli (7 log CFU reduction), using 50 nM of IP-H-OH2+ and just 1.36 J/cm2 light dose. The success of combining PDI with this natural compound broadens the scope of therapies for MDR infections that do not add drug resistance. In vivo studies on a mouse model of wound infection showed the potential of cationic 5,15-di-imidazolyl porphyrins to treat clinically relevant infected wounds.

Photodynamic Therapy With RLP068 and 630-nm Red LED Light in Foot Ulcers in Patients With Diabetes: A Case Series

The management and healing of lower extremity ulcers have always been a complex health problem because the clinical course is typically chronic, the results are often poor, and the socioeconomic impact is considerable. The healing process of foot ulcers of people with diabetes is further hindered by the concomitant presence of obstructive arterial disease, neuropathy, and foot malformation. It is frequently associated with multiresistant infections and often results in micro/macro amputations. Photodynamic therapy employs a photosensitizer activated by light of a specific wavelength able to generate reactive oxygen species, which initiate further oxidative responses locally with components of the bacteria. The experience of the treatment center for the lower extremity ulcers in 17 persons with diabetes in Acerra (Italy) with photoactivated RLP068, reported here, corroborates the results of the clinical trials and of the previous case reports. In all cases, examined photodynamic therapy with photosensitizer RLP068 and red light at 630 nm was found to reduce lesion area and inflammation and to ensure the decrease of bacterial load, hence reducing treatment times and antibiotics use, improving patient outcomes, and reducing the incidence of amputations. The simultaneous combination of photodynamic therapy with other ancillary physical-based treatments such as therapeutic magnetic resonance or Bio-Electro-Magnetic-Energy-Regulation was observed to be safe, time-saving, and able to lead to faster healing.

Effects of photodynamic therapy in patients with infected skin ulcers: A meta-analysis

The purpose of the meta-analysis was to evaluate and compare the photodynamic therapy's effectiveness in treating infected skin wounds. The results of this meta-analysis were analysed, and the odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) were calculated using dichotomous or contentious random- or fixed-effect models. For the current meta-analysis, 6 examinations spanning from 2013 to 2021 were included, encompassing 154 patients with infected skin wounds were the used studies' starting point. Photodynamic therapy had a significantly lower wound ulcer size (MD, -4.42; 95% CI, -7.56--1.28, p = 0.006), better tissue repair (MD, -8.62; 95% CI, -16.76--0.48, p = 0.04) and lower microbial cell viability (OR, 0.13; 95% CI, 0.04-0.42, p < 0.001) compared with red light exposure in subjects with infected skin wounds. The examined data revealed that photodynamic therapy had a significantly lower wound ulcer size, better tissue repair and lower microbial cell viability compared with red light exposure in subjects with infected skin wounds. However, given that all examinations had a small sample size, consideration should be given to their values.

Photodynamic therapy for infected foot ulcers in people with diabetes mellitus: a systematic review

BACKGROUND

Ulceration of the feet in patients with diabetes is a frequent complication that increases morbidity, mortality, hospitalization, treatment costs, and non-traumatic amputations.

OBJECTIVE

To present a systematic review of the treatment of patients with diabetes mellitus and infected foot ulcers using photodynamic therapy.

DESIGN AND SETTING

A systematic review was performed in the postgraduate program in nursing at the Universidade da Integração Internacional da Lusofonia Afro-Brasileira, Ceará, Brazil.

METHODS

PubMed, CINAHL, Web of Science, EMBASE, Cochrane Library, Scopus, and LILACS databases were screened. The methodological quality, risk of bias, and quality of evidence of each study were assessed. Review Manager was used for the meta-analysis.

RESULTS

Four studies were included. They highlighted significantly better outcomes in patient groups treated with photodynamic therapy than those in the control groups that were treated with topical collagenase and chloramphenicol (P = 0.036), absorbent (P < 0.001), or dry covers (P = 0.002). Significant improvements were noted in terms of the microbial load in the ulcers and tissue repair, with a reported reduction in the need for amputation by up to 35 times. Photodynamic therapy resulted in significantly better outcomes between the experimental and control groups (P = 0.04).

CONCLUSION

Photodynamic therapy is significantly more effective in treating infected foot ulcers than standard therapies.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO) - CRD42020214187, https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=214187.

The first evidence of antibiofilm action of Proteus mirabilis with tetra-cationic porphyrins containing cisplatin by antimicrobial photodynamic therapy

Biofilms are responsible for up to 80% of antimicrobial-resistant nosocomial infections. Most of these infections are associated with medical devices such as urinary catheters, and in this context, it is estimated that 90-100% of patients who undergo long-term catheterization develop infections. Proteus mirabilis, the most prevalent microorganism, is responsible for 20-45% of these infections. Thus, this study aimed to evaluate, for the first time, the antimicrobial and antibiofilm effects of cationic porphyrins on P. mirabilis. Neutral porphyrins 3-H₂TPyP and 4-H₂TpyP and tetra-cationic derivatives 3-cis-PtTPyP and 4-cis-PtTPyP were evaluated in broth microdilution tests to determine the minimum inhibitory and bactericidal concentrations. Time-kill curves, checkerboard test, reactive oxygen species (ROS) scavenger assays, conventional biofilm formation, and biofilm assay with catheters were also performed. The microdilution tests showed greater efficacy against P. mirabilis when 3-cis-PtTPyP was exposed to white-light conditions; this also occurred when the microbial time-kill curve was performed at 0, 2, 6, and 12 h. The radical superoxide species was possibly responsible for photoinactivation in the ROS scavenger assays. In biofilm assays (conventional and catheter), 3-cis-PtTPyP obtained better results when irradiated with a white-light source. In the checkerboard assay, the same compound showed no differences when tested in association with ciprofloxacin hydrochloride. Our findings lead us to conclude that antimicrobial photodynamic therapy and cationic porphyrins obtained positive results and are promising alternatives to treat P. mirabilis biofilms.

Photodynamic therapy for treating infected skin wounds: A systematic review and meta-analysis from randomized clinical trials

BACKGROUND

Infected skin wounds represent a public health problem that effects 20 million people worldwide. Photodynamic therapy (PDT) is a treatment option with excellent results against several infections.

OBJECTIVE

This study aimed to perform a systematic review and meta-analysis on PDT efficacy for treating infected wounds based on randomized clinical trials (RCTs).

METHODS

PubMed, Scopus, Web of Science, SciELO, and the Cochrane library were searched. The Delphi List criteria and the Revised Cochrane risk-of-bias (Rob 2) were used for evaluating the quality of clinical trials. Meta-analyses were performed with the random-effect model. The odds ratio was the effect measure for binary outcomes, while the standard mean difference was used for continuous outcomes. The trim-and-fill method was used to detect small-study effects. The quality of evidence was verified for each outcome.

RESULTS

Only four out of 573 articles were selected for the qualitative and quantitative analyses. The most frequent cause of infected wounds was impaired venous circulation (75%). All studies used red LED light. PDT reduced healing time and improved the healing process and wound oxygenation. Patients treated with PDT showed 15% to 17% (p = 0.0003/ I²=0%) lower microbial cell viability in the wound and a significantly smaller wound size (0.72 cm²/p = 0.0187/I²=0%) than patients treated with placebo or red-light exposure. There was a high level of evidence for each meta-analysis outcome.

CONCLUSION

PDT can be an excellent alternative treatment for infected skin wounds, though larger trials are needed.

The photosensitizer-based therapies enhance the repairing of skin wounds

Wound repair remains a clinical challenge and bacterial infection is a common complication that may significantly delay healing. Therefore, proper and effective wound management is essential. The photosensitizer-based therapies mainly stimulate the photosensitizer to generate reactive oxygen species through appropriate excitation source irradiation, thereby killing pathogenic microorganisms. Moreover, they initiate local immune responses by inducing the recruitment of immune cells as well as the production of proinflammatory cytokines. In addition, these therapies can stimulate the proliferation, migration and differentiation of skin resident cells, and improve the deposition of extracellular matrix; subsequently, they promote the re-epithelialization, angiogenesis, and tissue remodeling. Studies in multiple animal models and human skin wounds have proved that the superior sterilization property and biological effects of photosensitizer-based therapies during different stages of wound repair. In this review, we summarize the recent advances in photosensitizer-based therapies for enhancing tissue regeneration, and suggest more effective therapeutics for patients with skin wounds.

Synergic dual phototherapy: Cationic imidazolyl photosensitizers and ciprofloxacin for eradication of in vitro and in vivo E. coli infections

The emergence of new microorganisms with resistance to current antimicrobials is one of the key issues of modern healthcare that must be urgently addressed with the development of new molecules and therapies. Photodynamic inactivation (PDI) in combination with antibiotics has been recently regarded as a promising wide-spectrum therapy for the treatment of localized topical infections. However, further studies are required regarding the selection of the best photosensitizer structures and protocol optimization, in order to maximize the efficiency of this synergic interaction. In this paper, we present results that demonstrate the influence of the structure of cationic imidazolyl-substituted photosensitizers and light on the enhancement of ciprofloxacin (CIP) activity, for the inactivation of Escherichia coli. Structure-activity studies have highlighted the tetra cationic imidazolyl porphyrin IP-H-Me⁴⁺ at sub-bactericide concentrations (4-16 nM) as the most promising photosensitizer for combination with sub-inhibitory CIP concentration (<0.25 mg/L). An optimized dual phototherapy protocol using this photosensitizer was translated to in vivo studies in mice wounds infected with E. coli. This synergic combination reduced the amount of photosensitizer and ciprofloxacin required for full E. coli inactivation and, in both in vitro and in vivo studies, the combination therapy was clearly superior to each monotherapy (PDI or ciprofloxacin alone). Overall, these findings highlight the potential of cationic imidazolyl porphyrins in boosting the activity of antibiotics and lowering the probability of resistance development, which is essential for a sustainable long-term treatment of infectious diseases.

New Metallophthalocyanines Bearing 2-Methylimidazole Moieties-Potential Photosensitizers against Staphylococcus aureus

Newly developed tetra- and octasubstituted methimazole-phthalocyanine conjugates as potential photosensitizers have been obtained. Synthesized intermediates and final products were characterized by the MALD-TOF technique and various NMR techniques, including 2D methods. Single-crystal X-ray diffraction was used to determine the crystal structures of dinitriles. The studied phthalocyanines revealed two typical absorption bands—the Soret band and the Q band. The most intense fluorescence was observed for octasubstituted magnesium(II) phthalocyanine in DMF (Φ_FL = 0.022). The best singlet oxygen generators were octasubstituted magnesium(II) and zinc(II) phthalocyanines (Φ_∆ 0.56 and 0.81, respectively). The studied compounds presented quantum yields of photodegradation at the level between 10⁻⁵ and 10⁻⁶. Due to their low solubility in a water environment, the liposomal formulations were prepared. Within the studied group, octasubstituted zinc(II) phthalocyanine at the concentration of 100 µM activated with red light showed the highest antibacterial activity against S. aureus equal to a 5.68 log reduction of bacterial growth.

Antimicrobial Photodynamic Therapy: Latest Developments with a Focus on Combinatory Strategies

Antimicrobial photodynamic therapy (aPDT) has become a fundamental tool in modern therapeutics, notably due to the expanding versatility of photosensitizers (PSs) and the numerous possibilities to combine aPDT with other antimicrobial treatments to combat localized infections. After revisiting the basic principles of aPDT, this review first highlights the current state of the art of curative or preventive aPDT applications with relevant clinical trials. In addition, the most recent developments in photochemistry and photophysics as well as advanced carrier systems in the context of aPDT are provided, with a focus on the latest generations of efficient and versatile PSs and the progress towards hybrid-multicomponent systems. In particular, deeper insight into combinatory aPDT approaches is afforded, involving non-radiative or other light-based modalities. Selected aPDT perspectives are outlined, pointing out new strategies to target and treat microorganisms. Finally, the review works out the evolution of the conceptually simple PDT methodology towards a much more sophisticated, integrated, and innovative technology as an important element of potent antimicrobial strategies.

Photodynamic disinfection and its role in controlling infectious diseases

Photodynamic therapy is witnessing a revival of its origins as a response to the rise of multi-drug resistant infections and the shortage of new classes of antibiotics. Photodynamic disinfection (PDDI) of microorganisms is making progresses in preclinical models and in clinical cases, and the perception of its role in the clinical armamentarium for the management of infectious diseases is changing. We review the positioning of PDDI from the perspective of its ability to respond to clinical needs. Emphasis is placed on the pipeline of photosensitizers that proved effective to inactivate biofilms, showed efficacy in animal models of infectious diseases or reached clinical trials. Novel opportunities resulting from the COVID-19 pandemic are briefly discussed. The molecular features of promising photosensitizers are emphasized and contrasted with those of photosensitizers used in the treatment of solid tumors. The development of photosensitizers has been accompanied by the fabrication of a variety of affordable and customizable light sources. We critically discuss the combination between photosensitizer and light source properties that may leverage PDDI and expand its applications to wider markets. The success of PDDI in the management of infectious diseases will ultimately depend on the efficacy of photosensitizers, affordability of the light sources, simplicity of the procedures, and availability of fast and efficient treatments.

Follow-up of pressure ulcer treatment with photodynamic therapy, low level laser therapy and cellulose membrane

OBJECTIVE

A pressure ulcer (PU) is an area of tissue trauma caused by continuous and prolonged pressure, often associated with hospitalised patients immobilised due to neurological problems, negatively affecting their quality of life, and burdening the public budget. The aim of this study was to report the follow-up, for 45 weeks, of three patients with neurological lesions due to trauma who subsequently developed PUs, and who were treated with a combination of photodynamic therapy (PDT), low level laser therapy (LLLT) and cellulose membrane (CM).

METHOD

PDT was mediated by the photosensitiser curcumin on a 1.5% emulsion base. Blue LED light at 450 nm was delivered continuously for 12 minutes at an irradiance of 30mW/cm² and total energy delivered to the tissue was 22J/cm². LLLT was performed with 660 nm laser, punctuated and continuous, twice a week with parameters: spot size 0.04cm², power of 40mW, 10 seconds per point, fluence of 10J/cm² and irradiance of 1000mW/cm².

RESULTS

All PUs had a significant reduction (range: 95.2-100%) of their area after 45 weeks of follow-up and two PUs had complete healing at 20 weeks and 30 weeks. All of the PUs showed a reduction in contamination with the PDT treatments in different proportions.

CONCLUSION

From the results obtained, we conclude that the combination of PDT, LLLT and CM is a promising treatment for PU healing.

The Role of Porphyrinoid Photosensitizers for Skin Wound Healing

Microorganisms, usually bacteria and fungi, grow and spread in skin wounds, causing infections. These infections trigger the immune system and cause inflammation and tissue damage within the skin or wound, slowing down the healing process. The use of photodynamic therapy (PDT) to eradicate microorganisms has been regarded as a promising alternative to anti-infective therapies, such as those based on antibiotics, and more recently, is being considered for skin wound-healing, namely for infected wounds. Among the several molecules exploited as photosensitizers (PS), porphyrinoids exhibit suitable features for achieving those goals efficiently. The capability that these macrocycles display to generate reactive oxygen species (ROS) gives a significant contribution to the regenerative process. ROS are responsible for avoiding the development of infections by inactivating microorganisms such as bacteria but also by promoting cell proliferation through the activation of stem cells which regulates inflammatory factors and collagen remodeling. The PS can act solo or combined with several materials, such as polymers, hydrogels, nanotubes, or metal-organic frameworks (MOF), keeping both the microbial photoinactivation and healing/regenerative processes' effectiveness. This review highlights the developments on the combination of PDT approach and skin wound healing using natural and synthetic porphyrinoids, such as porphyrins, chlorins and phthalocyanines, as PS, as well as the prodrug 5-aminolevulinic acid (5-ALA), the natural precursor of protoporphyrin-IX (PP-IX).

New Perspective to Improve Care of Patients with Infected Diabetic Foot Ulcer: Early Economic Impact of the Use of Photodynamic Therapy with RLP068 (Based) System

Objective

To perform an early economic evaluation of a system based on photodynamic advanced adjuvant therapy with photosensitizer RLP068/CI to facilitate the healing process of foot/leg skin lesions/ulcers with an excellent safety profile.

Design

An early short-term (10 weeks) cost-effectiveness and a budget impact analysis (over 5 years) comparing photodynamic therapy with photosensitizer RLP068/CI based (PDT-RLP068) system added to Standard of Care (SoC) vs SoC alone.

Setting

The Italian National Healthcare System perspective considering both the outpatient and the day-hospital regimen.

Participants

Hypothetical patients with diabetic foot infection (DFI) grades I/IIB.

Interventions

The PDT-RLP068 system as an add-on to Standard of Care (SoC) vs SoC alone as the first-line treatment for the management of DFIs.

Main Outcomes

Days within which the clinical target was achieved and direct health costs for patients' management.

Results

Additional costs generated by the use of the PDT-RLP068 system progressively decreased as time to reach the target induced by the novel system decreased. In the outpatient regimen, when time to reach clinical target decreased in the range 7-28 days, ICERs varied from about 1€ to 70€ for each additional day gained with clinical target achieved. The system was dominant when halving time to reach the target in the outpatient regimen and even for modest reduction of time in day-hospital regimen. In terms of budget impact, when considering day-hospital regimen, if the PDT-RLP068 based system allowed a shortened duration to reach the clinical target of between 7-28 days, BI was 8,100,000€ to 700,000€, with saving less than 2,000,000€ with 50% reduction of time. Considering the inpatient setting, the use of the PDT-RLP068 system would result in saving even with the modest impact on the time needed to activate the healing process.

Conclusion

The early economic evaluation performed suggested that, if the claimed effectiveness of the technology demonstrated in case reports and in preliminary clinical studies can be confirmed in larger population studies, and allowing for shortening of the time needed to activate the healing process, the PDT-RLP068 system could offer the chance to improve care for DFI patients without compromising the sustainability of the system.

Photodynamic therapy to control microbial biofilms

Microorganisms thrive in well-organized biofilm ecosystems. Biofilm-associated cells typically show increased resistance to antibiotics and contribute significantly to treatment failure. This has prompted investigations aimed at developing advanced and novel antimicrobial approaches that could effectively overcome the shortcomings associated with conventional antibiotic therapy. Studies are ongoing to develop effective curative strategies ranging from the use of peptides, small molecules, nanoparticles to bacteriophages, sonic waves, and light energy targeting various structural and physiological aspects of biofilms. In photodynamic therapy, a light source of a specific wavelength is used to irradiate non-toxic photosensitizers such as tetrapyrroles, synthetic dyes or, naturally occurring compounds to generate reactive oxygen species that can exert a lethal effect on the microbe especially by disrupting the biofilm. The photosensitizer preferentially binds to and accumulates in the microbial cells without causing any damage to the host tissue. Currently, photodynamic therapy is increasingly being used for the treatment of oral caries and dental plaque, chronic wound infections, infected diabetic foot ulcers, cystic fibrosis, chronic sinusitis, implant device-associated infections, etc. This approach is recognized as safe, as it is non-toxic and minimally invasive, making it a reliable, realistic, and promising therapeutic strategy for reducing the microbial burden and biofilm formation in chronic infections. In this review article, we discuss the current and future potential strategies of utilizing photodynamic therapy to extend our ability to impede and eliminate biofilms in various medical conditions.

Photodynamic Topical Antimicrobial Therapy for Infected Diabetic Foot Ulcers in Patients With Diabetes: A Case Series

Diabetic foot ulcers (DFUs) are common, complex, costly complications, associated with frequent recurrences and increased morbidity and mortality. DFUs can be prevented and their healing can be mostly influenced by appropriately and aggressively managing any infection, but the role of antiseptic therapies in reducing healing time lacks sufficient evidence. Several therapeutic interventions have been developed based on the principles of photomedicine to overcome the issue of poor drug circulation in infected areas, with the aim of killing microbial agents while leaving the surrounding host cells unharmed. Such techniques use absorption of photons by specific chromophores. Among these, RLP068 is a tetracationic Zn(II) phthalocyanine derivative activated by exposure to red light, used as a topical treatment for superficial bacterial and fungal infections. The photoactivation of RLP068 results in the production of singlet oxygen and other reactive oxygen species, able to affect a range of cellular targets, including cell membrane and/or wall, cytoplasm, and cellular components, resulting in a rapid, broad range, bactericidal and fungicidal effect. The phase IIa study showed that photoactivated RPL068 is capable of inducing a dose-dependent reduction in total and pathogen microbial load in infected diabetic foot ulcers. In this article, a case series of 22 DFU treated with photoactivated RLP068 at 5 different centers in Italy is presented. Considering microbial agents reduction, ulcer healing facilitation, healing rate (9 DFUs out of 22), and amputation rate (only 1 case over 22), the decrease in the cost of DFU seems to be a point in favor of RLP068 and its cost-effectiveness.

Interventions in the management of infection in the foot in diabetes: a systematic review

The optimal approaches to managing diabetic foot infections remain a challenge for clinicians. Despite an exponential rise in publications investigating different treatment strategies, the various agents studied generally produce comparable results, and high-quality data are scarce. In this systematic review, we searched the medical literature using the PubMed and Embase databases for published studies on the treatment of diabetic foot infections as of June 2018. This systematic review is an update of previous reviews, the first of which was undertaken in 2010 and the most recent in 2014, by the infection committee of the International Working Group of the Diabetic Foot. We defined the context of literature by formulating clinical questions of interest, then developing structured clinical questions (PICOs) to address these. We only included data from controlled studies of an intervention to prevent or cure a diabetic foot infection. Two independent reviewers selected articles for inclusion and then assessed their relevant outcomes and the methodological quality. Our literature search identified a total of 15 327 articles, of which we selected 48 for full-text review; we added five more studies discovered by means other than the systematic literature search. Among these selected articles were 11 high-quality studies published in the last 4 years and two Cochrane systematic reviews. Overall, the outcomes in patients treated with the different antibiotic regimens for both skin and soft tissue infection and osteomyelitis of the diabetic foot were broadly equivalent across studies, except that treatment with tigecycline was inferior to ertapenem (±vancomycin). Similar outcomes were also reported in studies comparing primarily surgical and predominantly antibiotic treatment strategies in selected patients with diabetic foot osteomyelitis. There is insufficient high-quality evidence to assess the effect of various adjunctive therapies, such as negative pressure wound therapy, topical ointments or hyperbaric oxygen, on infection related outcomes of the diabetic foot. In general, the quality of more recent trial designs are better in past years, but there is still a great need for further well-designed trials to produce higher quality evidence to underpin our recommendations.

Guidelines on the diagnosis and treatment of foot infection in persons with diabetes (IWGDF 2019 update)

The International Working Group on the Diabetic Foot (IWGDF) has published evidence-based guidelines on the prevention and management of diabetic foot disease since 1999. This guideline is on the diagnosis and treatment of foot infection in persons with diabetes and updates the 2015 IWGDF infection guideline. On the basis of patient, intervention, comparison, outcomes (PICOs) developed by the infection committee, in conjunction with internal and external reviewers and consultants, and on systematic reviews the committee conducted on the diagnosis of infection (new) and treatment of infection (updated from 2015), we offer 27 recommendations. These cover various aspects of diagnosing soft tissue and bone infection, including the classification scheme for diagnosing infection and its severity. Of note, we have updated this scheme for the first time since we developed it 15 years ago. We also review the microbiology of diabetic foot infections, including how to collect samples and to process them to identify causative pathogens. Finally, we discuss the approach to treating diabetic foot infections, including selecting appropriate empiric and definitive antimicrobial therapy for soft tissue and for bone infections, when and how to approach surgical treatment, and which adjunctive treatments we think are or are not useful for the infectious aspects of diabetic foot problems. For this version of the guideline, we also updated four tables and one figure from the 2016 guideline. We think that following the principles of diagnosing and treating diabetic foot infections outlined in this guideline can help clinicians to provide better care for these patients.

Efficacy and safety of photodynamic therapy with RLP068 for diabetic foot ulcers: a review of the literature and clinical experience

This article is the second part of a literature review concerning diabetic foot ulcers (DFUs) and the use of antimicrobial photodynamic therapy (PDT). PDT involves the topical application of a photosensitiser into the tissue, followed by illumination that induces the formation of reactive oxygen species (ROS). PDT provides bacterial inactivation and promotes wound healing, and it can be used to manage the infection and microbial colonisation of DFUs. It has pivotal advantages in comparison with chemotherapeutics, such as no potential to induce resistance, and a wide spectrum of activity. Tetracationic Zn(II) phthalocyanine derivatives have been developed for PDT. Among these, we would like to focus on RLP068, whose antimicrobial activity has been widely demonstrated in preclinical studies and in a clinical trial. This article reports previously published evidence and presents four unpublished clinical cases of DFUs treated in the real-life setting with PDT.

Antimicrobial Photodynamic Therapy in Infected Diabetic Foot Ulcers: A Multicenter Preliminary Experience

BACKGROUND

The increasing resistance of bacteria to antibiotics and the frequency of comorbid conditions of patients make the treatment of diabetic foot infections problematic. In this context, photodynamic therapy could be a useful tool to treat infected wounds. The aim of this study was to evaluate the effect of repeated applications of a phthalocyanine derivative (RLP068) on the bacterial load and on the healing process.

METHODS

The present analysis was performed on patients with clinically infected ulcers who had been treated with RLP068. A sample for microbiological culture was collected at the first visit before and immediately after the application of RLP068 on the ulcer surface, and the area was illuminated for 8 minutes with a red light. The whole procedure was repeated three times per week at two centers (Florence and Arezzo, Italy) (sample A), and two times per week at the third center (Stuttgart, Germany) (sample B) for 2 weeks.

RESULTS

Sample A and sample B were composed of 55 and nine patients, respectively. In sample A, bacterial load decreased significantly after a single treatment, and the benefit persisted for 2 weeks. Similar effects of the first treatment were observed in sample B. In both samples, the ulcer area showed a significant reduction during follow-up, even in patients with ulcers infected with gram-negative germs or with exposed bone.

CONCLUSIONS

RLP068 seems to be a promising topical wound management procedure for the treatment of infected diabetic foot ulcers.

Photodynamic therapy in infected venous and mixed leg ulcers: a pilot experience

OBJECTIVE

To assess the tolerability and efficacy of photodynamic therapy (PDT) with RLP068, a novel phthalocyanine-derived photosensitiser, in controlling the bacterial load in different leg ulcers, due to vascular pathophysiology.

METHOD

An observational study of patients with infected leg ulcers of different pathophysiology, admitted to the hospital for a skin grafting procedure, were included. All patients underwent two sessions of PDT at time zero and after 72 hours. A semi-quantitative swab was taken before and 30 minutes after both sessions of PTD. During the time interval between the two treatments the ulcer was covered with foam dressing and compression therapy was applied to all patients. No systemic or topical antibiotics were administered. Statistical analysis of results was performed.

RESULTS

A total of 36 patients (13 males, 23 females; aged 72.4±8.6 years, range: 55-85 years) were recruited; two had ulcers on both legs. PDT was shown to be effective in reducing bacterial load after the first treatment. Before the second PDT treatment (72 hours after first PDT treatment), a slight increase of the bacterial load was observed in all ulcers. However, after the second PDT session, bacterial swab results were negative in all but two ulcers. The procedure was well tolerated in all but four patients, who reported a very severe pain at baseline, which increased during treatment.

CONCLUSION

In this study, PDT was effective in reducing bacterial load in patients with infected vascular leg ulcers, and allowed successful skin grafting to take place in all patients. The treatment was generally well tolerated. Studies with a greater number of patients and a control group are planned to confirm these results.

The benefits of antimicrobial photodynamic therapy with RLP068 in the management of diabetic foot ulcers

This article is the first part of a literature review concerning diabetic foot ulcers and the use of antimicrobial photodynamic therapy (PDT). Diabetic foot ulcers are associated with high morbidity, mortality, and healthcare costs. Natural healing is often delayed by microbial infection or colonisation, which might lead to serious complications, such as amputation. Furthermore, antibiotic treatment could have limited success because of the development of bacterial resistance and severely limited drug delivery to the ulcer due to vascular damage. PDT has antimicrobial effects and has been used to reduce the total and pathogenic microbial load in diabetic ulcers without inducing bacterial resistance. It is safe and can be used to improve outcomes. A clinical trial demonstrated that PDT with RLP068 reduced the microbial load of diabetic ulcers in 62 patients. This article reports previously published evidence and presents four, unpublished, clinical cases treated in the real-life setting.

In vitro Evaluation of Photodynamic Effects Against Biofilms of Dermatophytes Involved in Onychomycosis

Dermatophytes are the most common cause of onychomycosis, counting for 90% fungal nail infection. Although dermatophyte pathogens are normally susceptible to antifungal agents, onychomycosis often results in refractory chronic disease, and the formation of biofilms frequently underlines the inadequate responses and resistance to standard antifungal treatment. Numerous in vitro and in vivo antimicrobial photodynamic therapy (aPDT) studies have shown biofilm eradication or substantial reduction, however, such investigation has not yet been expanded to the biofilms of dermatophytes involved in onychomycosis. To shed a light on the potential application of aPDT in the clinic management of onychomycosis, in particular with the manifestation of dermatophytoma, we investigated photodynamic effects on the viabilities and the drug susceptibilities of the biofilm of dermatophytes in vitro. Here, methylene blue at the concentration of 8, 16, and 32 μg/ml applied as photosensitizing agent and LED (635 ± 10 nm, 60 J/cm²) as light source were employed against six strains of Trichophyton rubrum, ten strains of Trichophyton mentagrophytes and three strains of Microsporum gypseum isolated from clinical specimens. Our results indicated highly efficient photodynamic inhibition, exhibiting CFU (colony forming unit) reduction up to 4.6 log₁₀, 4.3 log₁₀, and 4.7 log₁₀ against the biofilms formed by T. rubrum, T. mentagrophytes, and M. gypseum, respectively. Subjected biofilms displayed considerable decreases in SMICs (sessile minimum inhibitory concentrations) to multiple antifungal agents when compared with untreated groups, indicating the biofilms of dermatophytes became more susceptible to conventional antifungal drugs after aPDT. Additionally, the obliteration of biofilm after aPDT could be observed as shattered and ruptured structures being evident in SEM (Scanning Electron Microscopy) images. These findings suggest that aPDT is an attractive alternative treatment holding great promise for combating recalcitrant onychomycosis associated with the biofilm formation.

Nonconventional Therapeutics against Staphylococcus aureus

Staphylococcus aureus is one of the most important human pathogens that is responsible for a variety of diseases ranging from skin and soft tissue infections to endocarditis and sepsis. In recent decades, the treatment of staphylococcal infections has become increasingly difficult as the prevalence of multi-drug resistant strains continues to rise. With increasing mortality rates and medical costs associated with drug resistant strains, there is an urgent need for alternative therapeutic options. Many innovative strategies for alternative drug development are being pursued, including disruption of biofilms, inhibition of virulence factor production, bacteriophage-derived antimicrobials, anti-staphylococcal vaccines, and light-based therapies. While many compounds and methods still need further study to determine their feasibility, some are quickly approaching clinical application and may be available in the near future.

Antimicrobial Photodynamic Therapy to Control Clinically Relevant Biofilm Infections

Biofilm describes a microbially-derived sessile community in which microbial cells are firmly attached to the substratum and embedded in extracellular polymeric matrix. Microbial biofilms account for up to 80% of all bacterial and fungal infections in humans. Biofilm-associated pathogens are particularly resistant to antibiotic treatment, and thus novel antibiofilm approaches needed to be developed. Antimicrobial Photodynamic therapy (aPDT) had been recently proposed to combat clinically relevant biofilms such as dental biofilms, ventilator associated pneumonia, chronic wound infections, oral candidiasis, and chronic rhinosinusitis. aPDT uses non-toxic dyes called photosensitizers (PS), which can be excited by harmless visible light to produce reactive oxygen species (ROS). aPDT is a multi-stage process including topical PS administration, light irradiation, and interaction of the excited state with ambient oxygen. Numerous in vitro and in vivo aPDT studies have demonstrated biofilm-eradication or substantial reduction. ROS are produced upon photo-activation and attack adjacent targets, including proteins, lipids, and nucleic acids present within the biofilm matrix, on the cell surface and inside the microbial cells. Damage to non-specific targets leads to the destruction of both planktonic cells and biofilms. The review aims to summarize the progress of aPDT in destroying biofilms and the mechanisms mediated by ROS. Finally, a brief section provides suggestions for future research.

Antimicrobial effects of photodynamic therapy

The microorganisms that cause infections are increasing their resistance to antibiotics. In this context, alternative treatments are necessary. The antimicrobial photodynamic therapy (aPDT) is a therapeutic modality based on photosensitizing molecules that end up generating reactive oxygen species that induce the destruction of the target cells when are irradiated with light of a suitable wavelength and at a proper dose. The cells targeted by aPDT are all types of microorganisms (bacteria, fungi and parasites) including viruses and has been proven effective against representative members of all of them. In the field of dermatology, aPDT has been tested with promising results in different infections such as chronic ulcers, acne, onychomycosis and other cutaneous mycoses, as well as in leishmaniasis. Therefore, it is presented as a possible treatment option against the agents that cause skin and/or mucous infections.

The effects of photobiomodulation therapy on Staphylococcus aureus infected surgical wounds in diabetic rats. A microbiological, histopathological, and biomechanical study

PURPOSE

To evaluate the effects of photobiomodulation therapy (PBMT) at 685 nm on diabetic wound healing in rats suffering from bacterial infection induced by Staphylococcus aureus (S. aureus).

METHODS

Thirty streptozotocin-induced diabetic rats were allocated into two groups: control and PBMT. A 4-cm full-thickness linear-incision was made on the dorsal midline and was contaminated with S. aureus. The wounds in the PBMT group were irradiated daily for 5 consecutive days, starting 3 days after the induction and always in the mornings.

RESULTS

The result revealed that PBMT resulted in a significant decrease in S. aureus CFU in the PBMT group in comparison to the control group (P<0.05). The length of wounds, in the 2nd and 3rd weeks, in the PBMT group were significantly shorter compared to the control group (P<0.05). PBMT caused a significant increase in the histological parameters in comparison to the control group (P<0.05). Moreover, PBMT significantly increased the breaking strength of the surgical scars produced in the skin of the PBMT group when compared to the control group (P<0.05).

CONCLUSION

Photobiomodulation therapy may be useful in the management of wound infection through a significant bacterial growth inhibition and an acceleration of wound healing process.

New photosensitizers for photodynamic therapy

Photodynamic therapy (PDT) was discovered more than 100 years ago, and has since become a well-studied therapy for cancer and various non-malignant diseases including infections. PDT uses photosensitizers (PSs, non-toxic dyes) that are activated by absorption of visible light to initially form the excited singlet state, followed by transition to the long-lived excited triplet state. This triplet state can undergo photochemical reactions in the presence of oxygen to form reactive oxygen species (including singlet oxygen) that can destroy cancer cells, pathogenic microbes and unwanted tissue. The dual-specificity of PDT relies on accumulation of the PS in diseased tissue and also on localized light delivery. Tetrapyrrole structures such as porphyrins, chlorins, bacteriochlorins and phthalocyanines with appropriate functionalization have been widely investigated in PDT, and several compounds have received clinical approval. Other molecular structures including the synthetic dyes classes as phenothiazinium, squaraine and BODIPY (boron-dipyrromethene), transition metal complexes, and natural products such as hypericin, riboflavin and curcumin have been investigated. Targeted PDT uses PSs conjugated to antibodies, peptides, proteins and other ligands with specific cellular receptors. Nanotechnology has made a significant contribution to PDT, giving rise to approaches such as nanoparticle delivery, fullerene-based PSs, titania photocatalysis, and the use of upconverting nanoparticles to increase light penetration into tissue. Future directions include photochemical internalization, genetically encoded protein PSs, theranostics, two-photon absorption PDT, and sonodynamic therapy using ultrasound.

Topical antimicrobial photodynamic therapy improves angiogenesis in wounds of diabetic mice

We report the results of our investigations on the effect of antimicrobial photodynamic therapy (APDT) on angiogenesis in wounds of diabetic mice. For this, measurements were made on levels of nitric oxide (NO), vascular endothelial growth factor-A (VEGF-A), and markers of proinflammatory stress (phosphorylated nuclear factor kappa B and p(38) mitogen-activated protein kinase) on day 3 post-wounding. For uninfected and infected wounds, the levels of NO, VEGF-A were lower and the levels of phospho-NF-kB-p65, phospho-p(38)MAPK were higher in diabetic mice compared with that in nondiabetic mice. For infected wounds, multiple APDT (fluence ~60 J/cm(2)) led to increase in NO, VEGF-A levels and a decrease in the phospho-NF-kB-p65, phospho-p(38)MAPK. Further, compared with aminoguanidine, and silver nitrate, multiple APDT was observed to result in a much improved proangiogenic response.

In diabetic foot infections antibiotics are to treat infection, not to heal wounds

INTRODUCTION

Diabetic foot ulcers, especially when they become infected, are a leading cause of morbidity and may lead to severe consequences, such as amputation. Optimal treatment of these diabetic foot problems usually requires a multidisciplinary approach, typically including wound debridement, pressure off-loading, glycemic control, surgical interventions and occasionally other adjunctive measures.

AREAS COVERED

Antibiotic therapy is required for most clinically infected wounds, but not for uninfected ulcers. Unfortunately, clinicians often prescribe antibiotics when they are not indicated, and even when indicated the regimen is frequently broader spectrum than needed and given for longer than necessary. Many agents are available for intravenous, oral or topical therapy, but no single antibiotic or combination is optimal. Overuse of antibiotics has negative effects for the patient, the health care system and society. Unnecessary antibiotic therapy further promotes the problem of antibiotic resistance.

EXPERT OPINION

The rationale for prescribing topical, oral or parenteral antibiotics for patients with a diabetic foot wound is to treat clinically evident infection. Available published evidence suggests that there is no reason to prescribe antibiotic therapy for an uninfected foot wound as either prophylaxis against infection or in the hope that it will hasten healing of the wound.

Coronary artery disease as an independent predictor of survival in patients with type 2 diabetes and Charcot neuro-osteoarthropathy

AIMS

Charcot neuro-osteoarthropathy (CN) is a rare complication of diabetic foot syndrome associated with chronic inflammation of the foot and severe, limb-threatening musculoskeletal deformities. Aim of this study was to investigate patients with CN for comorbidities, amputations, ulcers, secondary diseases and mortality.

METHODS

The study was conducted at a specialized German hospital for patients with diabetes. One-hundred and eleven patients were enrolled, and their course was followed over a period of 15 years. Association of CN with comorbidity, foot ulcers, amputations and mortality was assessed. Clinical course of patients was followed using two standardized questionnaires.

RESULTS

Presence of CN was significantly associated with diabetic retinopathy (p = 0.047), plantar (p < 0.001), tarsal (p = 0.032) and middle-foot ulcers (p = 0.01). A significant correlation between the presence of CN and a history of amputations was seen (p = 0.022). Patients were at increased risk to suffer from subsequent amputations during follow-up when micro- and macrovascular comorbidities such as retinopathy (p = 0.01) and peripheral artery disease (p < 0.001) were present. Additionally, coronary artery disease (CHD) was identified as an independent predictor of mortality in the cohort of this study (OR 6.192, 95 % CI 1.155-33.208, p = 0.033). Median overall survival of patients with CN and CHD was significantly shorter than OS of patients without CHD (7.8 vs. 13.1 years, p = 0.0045, HR 2.8437, 95 % CI 0.9818-8.2364).

CONCLUSIONS

In our study, CHD was the most important factor of survival in CN patients. For optimal management of CN, adequate diagnostics and treatment of CHD according to current guidelines should be considered.