Photodynamic nasal decolonization is a prophylactic technology utilizing a photosensitizer activated by light to induce photochemical reactions, which rapidly and effectively eliminate pathogens without harming human tissue. Eliminating nasal-borne pathogens before surgery significantly reduces risk of infection and pathogen transmission. We report an exploratory study performed in 35 healthy volunteers in which nasal microbial population responses were characterized over time, following photodynamic nasal decolonization (Steriwave®, Ondine Biomedical Inc., Vancouver, BC, Canada). Plate culture and 16s sequencing of nasal swab samples revealed a highly significant reduction in the number of viable bacterial cells and species immediately following treatment. Over time, the microbial population returned to its initial diversity level (24 hours) and quantitative number (48 hours). This is consistent with the design intent for a powerful, non-selective bactericidal modality allowing return to microbiome baseline less than 1-week post-treatment, thereby reducing the potential for long-term microbiome disturbances.
KEYWORDS: In vivo imaging, Photodynamic therapy, Picosecond phenomena, In vitro testing, Diffusers, Personal digital assistants, Standards development, Minerals, Fungi, Chemical elements
Aspergillus fumigatus is the most common isolated agent in chronic invasive fungal rhinosinusitis with patients enduring painful and recurrent sinus symptoms. Prompt diagnosis and initiation of appropriate therapy is essential to avoid a protracted or fatal outcome. Our group has developed a novel methylene blue-based photodynamic therapy approach to treatment of Aspergillus rhinosinusitis. Briefly, A. fumigatus was encapsulated within 250μm agar beads in a validated model and titrated into the rabbit maxillary sinus. A. fumigatus burden after Sinuwave™ antimicrobial photodynamic therapy was compared to control, with > 99.9% reduction in recoverable fungus, a highly significant outcome.
Photodynamic therapy(PDT) has been demonstrated to effectively kill human periopathogens in vitro. To evaluate the
efficacy of PDT in vivo a series of clinical trials was carried out in multiple centers and populations. Clinical parameters
including clinical attachment level, pocket probing depth and bleeding on probing were all evaluated. All groups
received the standard of care, scaling and root planing, and the treatment group additionally received a single treatment
of PDT. Of the total 309 patients and over 40,000 pockets treated in these 5 trials it was determined that photodynamic
therapy provided a statistically significant improvement in clinical parameters over scaling and root planing alone.
The nosocomial infection rate has increased dramatically due to emergence of antibiotic resistant bacterial strains such as
methicillin resistant Staphylococcus aureus (MRSA). The primary anatomical site of MRSA colonization is the anterior
nares, and this reservoir represents a primary vector of transmission from non-infected carriers to susceptible individuals.
Antimicrobial photodynamic therapy (aPDT) has been used successfully for topical disinfection in the oral cavity. The
aim of this study was to evaluate the utility of aPDT for nasal MRSA decolonization at the preclinical and clinical level.
The nasal aPDT system consists of a 670 nm diode laser fibre-optically coupled to a disposable light diffusing tip, used
to activate a methylene blue based photosensitizer formulation. Preclinical testing was done both in a custom nasal
reservoir model and on human skin cultures colonized on the epithelial surface with MRSA. Human clinical testing was
performed by clinicians in regions in which the system is approved by the regulatory authority. In vitro testing
demonstrated that aPDT eradicated planktonic MRSA in an energy and photosensitizer concentration dependent manner.
Furthermore, 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. Energy
dose and photosensitizer parameters have been optimized for the nasal environment. Controlled clinical studies are
currently underway to further evaluate safety and efficacy.
Photodynamic therapy has been demonstrated to effectively kill human periopathogens in vitro. However, the translation
of in vitro work to in vivo clinical efficacy has been difficult due to the number of variables present in any given patient.
Parameters such as photosensitizer concentration, duration of light therapy and amount of light delivered to the target
tissue all play a role in the dose response of PDT in vivo. In this 121 patient study we kept all parameters the same except
for light dose which was delivered at either 150 mW or 220 mW. This clearly demonstrated the clinical benefits of a
higher light dose in the treatment of periodontitis.
Periodontitis affects half of the U.S. population over 50, and is the leading cause of tooth loss after 35. It is believed to
be caused by growth of complex bacterial biofilms on the tooth surface below the gumline. Photodynamic therapy, a
technology used commonly in antitumor applications, has more recently been shown to exhibit antimicrobial efficacy.
We have demonstrated eradication of the periopathogens Porphyromonas gingivalis, Fusobacterium nucleatum, and
Aggregatibacter actinomycetemcomitans in vitro using PeriowaveTM; a commercial photodisinfection system. In
addition, several clinical studies have now demonstrated the efficacy of this treatment. A pilot study in the U.S. showed
that 68% of patients treated with PeriowaveTM adjunctively to scaling and root planing (SRP) showed clinical attachment
level increase of >1 mm, as opposed to 30% with SRP alone. In a subsequent larger study, a second PeriowaveTM
treatment 6 weeks after initial treatment led to pocket depth improvements of >1.5 mm in 89% of patients. Finally, in the
most recent multicenter, randomized, examiner-blinded study conducted on 121 subjects in Canada, PeriowaveTM
treatment produced highly significant gains in attachment level (0.88 mm vs. 0.57 mm; p=0.003) and pocket depth (0.87
mm vs. 0.63 mm; p=0.01) as compared to SRP alone. In summary, PeriowaveTM demonstrated strong bactericidal
activity against known periopathogens, and treatment of periodontitis using this system produced significantly better
clinical outcomes than SRP alone. This, along with the absence of any adverse events in patients treated to date
demonstrates that PDT is a safe and effective treatment for adult chronic periodontitis.
Two-axis scanning is generally accomplished using two separate single-axis scanners. In order to improve the functionality of a dual-axis scanning system and eliminate aperture transfer problems, MedCam, Inc. has developed a two-axis single deflector scanner using MEMS and micromachining techniques. Various configurations of the MedCam microscanner have demonstrated large scan angles at high scan rates with aperture diameters ranging from 1 mm to 10 mm. The scanner is extremely compact and may be used in small, portable applications.
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