Photodynamic disinfection (aka aPDT = antimicrobial photodynamic therapy
General (application independent)
Numerous studies and literature reviews have found that photodynamic disinfection is effective at killing a broad spectrum of pathogens, including drug-resistant bacteria, viruses, and fungi, while also inactivating inflammatory cytokines, helping speed the process of healing. Photodynamic disinfection remains fully effective after many repeat treatments, showing no sign of engendering resistance formation.
Learn more on the aPDT Wikipedia Page.
How does photodynamic disinfection or antimicrobial PDT work?
Publications
Photodisinfection Therapy: Essential Technology for Infection Control (peer-reviewed whitepaper)
Summary: Given its demonstrated ability to eradicate pathogenic microorganisms without inducing resistance following repeated exposure to therapy, aPDT is likely to evolve into an essential tool for infection control and become a vital part of the solution to the global AMR crisis. [InfectionControl.tips, 2020]
Antimicrobial Photodynamic Therapy for Control of the Newly Emerging Nosocomial Pathogen, C. auris
Summary: aPDT can eradicate all clinical isolates of Candida auris tested in vitro, including multidrug-resistant strains, in less than 5 minutes of treatment. [Antimicrobial Resistance & Infection Control, 2019]
A pilot study of antimicrobial photodynamic therapy of encapsulated Aspergillus fumigatus in a rabbit maxillary sinus model (poster)
Summary: Topical in vivo aPDT was capable of eradicating >3 log10 (>99.9%) of A.fumigatus inoculated into the NZW rabbit maxillary sinus in a recognized agar bead model of aspergillosis. This represents a >4,000-fold reduction in the number of viable conidia per unit area. These in vivo results closely matched in vitro experimental data in planktonic and biofilm cultures. [17th International Photodynamic Association World Congress, 2019]
Antimicrobial Photodynamic Therapy: A Decade of Development and Clinical Study (book chapter)
Summary: Key attributes of aPDT include a wide therapeutic window, high efficacy against polymicrobial biofilms, avoidance of the resistance issues that plague antibiotic usage, potent anti-inflammatory effects and activation of both innate and adaptive arms of the immune system. Treatment time is short, adverse effects are minimal to non-existent and no patient compliance is required. [Photodynamic Medicine: From Bench to Clinic, 2016]
The effect of light-activated antimicrobial agents on bacterial virulence factors and key modulators of inflammation (thesis)
Summary: aPDT reduces bacterial burden, bacterial virulence factors & proinflammatory cytokines. [University College London, 2011]
Absence of Bacterial Resistance Following Repeat Exposure to Photodynamic Therapy
Summary: aPDT is effective in the eradication of pathogens including antibiotic resistance strains. Repeated sub-lethal exposure does not induce resistance to subsequent aPDT treatments, which represents a significant advantage of aPDT over traditional antibiotics. [SPIE 7380 Photodynamic Therapy: Back to the Future, 2009]
In vitro photodynamic eradication of Pseudomonas aeruginosa in planktonic and biofilm culture
Summary: aPDT is effective in eradicating planktonic and biofilm cultures of P. aeruginosa, supporting the concept that translation into clinical practice for indications such as otitis externa and wound disinfection is a viable option. [Photochemistry and Photobiology, 2009]
Repeat Exposure of Bacterial Pathogens to Photodynamic Disinfection does not Induce Resistance Formation (poster)
Summary: aPDT eradicates Gram-negative and Gram-positive organisms regardless of antibiotic resistance. [International Conference on Antimicrobial Agents & Chemotherapy, 2008]
Nasal Decolonization
Nasal Photodisinfection has been in clinical use for over seven years and over 50,000 patients have been treated to date. It has been shown to reduce surgical site infections by 42-78%, preventing millions of dollars annually in infections, is well-received by patients and has compliance of nearly 100%. There have been no significant adverse events reported.
Publications
The efficacy and cost-effectiveness of photodynamic therapy in prevention of surgical site infection (abstract)
n= ~8000
Summary: aPDT nasal decolonization is both efficacious and cost-effective in preventing surgical site infection, particularly in complex instrumented cases in the highest risk patients. The study authors recommend routine use for SSI prevention. [The Spine Journal, 2019]
Nasal photodisinfection and chlorhexidine wipes decrease surgical site infections: a historical control study and propensity analysis
n = 3068
Summary: aPDT nasal decolonization together with chlorhexidine skin wipes preoperatively significantly reduced surgical site infections and costs. [Journal of Hospital Infection, 2014]
Nasal Decolonization of Methicillin-Resistant Staphylococcus aureus Using Antimicrobial Photodynamic Therapy (abstract)
n = 11
Summary: aPDT is effective against S. aureus/MRSA at the preclinical level without causing damage to human tissues. Human testing also showed that aPDT can achieve full nasal decolonization of these pathogens with relatively short treatment times. [Infectious Disease Society of America, 2011]
Antimicrobial Photodynamic Therapy for the Decolonization of Methicillin-Resistant Staphylococcus aureus from the Anterior Nares
Summary: aPDT effectively killed both planktonic and skin culture MRSA. In vitro aPDT eradicated planktonic MRSA in an energy and photosensitizer concentration dependent manner. aPDT eliminated sustained colonization of MRSA on cultured human epithelial surfaces, an effect that was sustained over multiple days post-treatment. In preliminary human testing, aPDT eradicated MRSA completely from the nose with total treatment times <10 minutes. aPDT is effective against MRSA when used topically in the nose. [SPIE 7380 Photodynamic Therapy: Back to the Future, 2009]
Periodontal Applications
Periodontal photodisinfection has been in clinical use for over a decade and over 600,000 treatments have been done worldwide to date. It has been shown to be effective at improving key periodontal outcomes (CAL = clinical attachment levels, PPD = periodontal pocket depth, and BOP = bleeding on probing) when used together with scaling and root planning (SRP) as compared to SRP alone. There have been no significant adverse events reported.
Publications
Antimicrobial Photodynamic Therapy in the Treatment of Chronic Adult Periodontitis
n = 34
Summary: Adjunctive aPDT provided significant gain in CAL and PPD reduction, compared to scaling and root planning (SRP) alone in treatment of chronic adult periodontitis. [Oral Health & Dental Science, 2018]
Photodynamic Disinfection in the Treatment of Chronic Adult Periodontitis: A Multicenter Clinical Trial
n = 121
Summary: aPDT using a methylene-based photosensitizer shows a distinct improvement in CAL and PPD over SRP alone in the treatment of chronic periodontitis. [Journal of Dental Health, Oral Disorders &Therapy, 2017]
Single or repeated antimicrobial photodynamic therapy as adjunct to ultrasonic debridement in residual periodontal pockets: clinical, microbiological, and local biological effects
n = 28
Summary: All groups responded. [Lasers in Medical Science, 2013]
The use of antimicrobial photodynamic therapy in the treatment of periodontitis (case series)
n = 90 pockets
Summary: Adjunctive aPDT improved outcomes for patients with periodontal disease. [Oral Health, 2012]
Comparison between scaling-root-planing (SRP) and SRP/photodynamic therapy: six-month study
n = 22
Summary: SRP in combination with aPDT is effective and is therefore suitable as an adjuvant therapy to the mechanical conditioning of the periodontal pockets in patients with chronic periodontal diseases. [Head and Face Medicine, 2012]
Adjunctive effect of photodynamic therapy to scaling and root planing in the treatment of chronic periodontitis
n = 58
Summary: aPDT demonstrated reduced bleeding in chronic periodontitis pockets as compared to SRP alone. [Photomedicine and Laser Surgery, 2011]
Chronic Rhinosinusitis (CRS) Treatment
Several studies have shown that Sinuwave Photodisinfection therapy is effective in treating bacteria and fungi common in CRS, without harm to the sinus cilia and respiratory mucosa. Early randomized trials have also demonstrated rapid improvement in both clinical and endoscopy scores (4x and 8x improvement respectively) sustained to at least six months.
Publications
Antimicrobial Photodynamic Therapy for Chronic Rhinosinusitis (oral presentation)
n = 48
Summary: aPDT for treatment of CRS after failed medical and surgical therapy provided improved outcomes over saline irrigation. [American Academy of Otolaryngology-HNSF & OTO Annual Meeting, 2016]
Sinuwave photodisinfection for the treatment of refractory chronic rhinosinusitis: a case series (poster)
n = 9
Summary: Patients with refractory CRS can be safely treated with aPDT under local anesthesia on an outpatient basis. Short term follow up in these patients has shown no delayed complications and importantly, demonstrated resolution of disease in several patients. [American Rhinologic Society Meeting, 2013]
Photodynamic therapy of antibiotic-resistant biofilms in a maxillary sinus model
Summary: aPDT can effectively treat CRS polymicrobial antibiotic resistant Pseudomonas aeruginosa and MRSA biofilms in a maxillary sinus cavity model. [International Forum of Allergy and Rhinology, 2013]
The Effect of Antimicrobial Photodynamic Therapy on Human Ciliated Respiratory Mucosa
Summary: aPDT is a safe treatment for CRS resulting in no histologic alteration of human ciliated respiratory mucosa as is found in the human sinuses. [The Laryngoscope, 2012]
Antimicrobial photodynamic therapy treatment of chronic recurrent sinusitis biofilms
Summary: aPDT can effectively treat CRS polymicrobial antibiotic-resistant bacteria, fungi, and biofilms in vivo. [International Forum of Allergy and Rhinology, 2011]
In vitro optimization of antimicrobial photodynamic therapy (aPDT) for eradication of mixed species biofilms representative of chronic rhinosinusitis (abstract)
Summary: aPDT is effective against polymicrobial biofilm. [13th International Photodynamic Association World Congress, 2011]
Other Applications (i.e. decolonization of ventilator tubes, burns, and wounds)
Studies of aPDT with various photosensitizers have found promising results in other applications.
Publications
Reduction of endotracheal tube biofilms using antimicrobial photodynamic therapy
Summary: aPDT can effectively treat polymicrobial antibiotic resistant biofilms in an endotracheal tube: reduced endotracheal tube polymicrobial biofilm in vitro by >99.9% (p<0.05%) after a single treatment. [Lasers in Surgery and Medicine, 2011]
Use of antimicrobial photodynamic therapy for prevention of HIV transmission from mother to child: A novel approach (poster)
Summary: aPDT sensitizer formulation alone produces some inactivation, but completely inactivates the virus when laser activated. Coupled with the well-known safety profile of MB in human use, initial results support development of an aPDT system designed to disinfect the birth canal during labor to reduce the rate of mother to child transmission of HIV. [Lasers in Surgery and Medicine, 2011]