An investigation into the inhibitory effect of ultraviolet radiation on Trichophyton rubrum (original) (raw)
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Lasers in Medical Science, 2014
The effective treatment of infected wounds continues to be a serious challenge, mainly due to the rise of antibiotic-resistant bacteria. Photodynamic therapy (PDT) refers to the topical or systemic administration of a non-toxic, photosensitizing agent (PS), followed by irradiation with visible light of a suitable wavelength. The possibility of applying the PDT locally is what makes it so favorable to the treatment of infected wounds. The goal of this study was to evaluate the action of the PDT in the inactivation in vitro of microorganisms coming from infected wounds, using methylene blue (MB) and photodithazine (PDZ) as the PS and comparing the efficacy of these two compounds for PDT on bacteria. For the application of PDT, isolated microorganisms identified from material collected from wounds were suspended in a saline solution containing 10 6 viable cells/ml. Each isolated microorganism was submitted to PDT with MB and with PDZ in accordance with the following treatment groups: N/T-no treatment; T1-PDT with PDZ; T2-PDT with MB; T3-irradiation without PS; T4-treatment with PDZ without light; and T5-treatment with MB without light. As a light source, an LED-based device was used (Biopdi/Irrad-Lead 660), composed of 54 LEDs, each with 70 mW of power in the 660 nm region of the electromagnetic spectrum. Each tray of 96 wells was irradiated with an intensity of 25 mW/cm 2 and a dose of light of 50 J/cm 3 for 33 min. All the tests were made in duplicate. It was then concluded that the PDT with PDZ was capable of inhibiting the growth of gram-positive bacteria samples, however it did not have the same effect on gramnegative bacteria, which showed growth greater than 100,000 CFU; the PDT with MB showed an effectiveness on gram-positive as well as gram-negative bacteria, for it was able to inhibit bacterial growth in both cases.
Light based anti-infectives: ultraviolet C irradiation, photodynamic therapy, blue light, and beyond
Current Opinion in Pharmacology, 2013
Owing to the worldwide increase in antibiotic resistance, researchers are investigating alternative anti-infective strategies to which it is supposed microorganisms will be unable to develop resistance. Prominent among these strategies, is a group of approaches which rely on light to deliver the killing blow. As is well known, ultraviolet light, particularly UVC (200-280nm), is germicidal, but it has not been much developed as an anti-infective approach until recently, when it was realized that the possible adverse effects to host tissue were relatively minor compared to its high activity in killing pathogens. Photodynamic therapy is the combination of non-toxic photosensitizing dyes with harmless visible light that together produce abundant destructive reactive oxygen species (ROS). Certain cationic dyes or photosensitizers have good specificity for binding to microbial cells while sparing host mammalian cells and can be used for treating many localized infections, both superficial and even deep-seated by using fiber optic delivered light. Many microbial cells are highly sensitive to killing by blue light (400-470 nm) due to accumulation of naturally occurring photosensitizers such as porphyrins and flavins. Near infrared light has also been shown to have antimicrobial effects against certain species. Clinical applications of these technologies include skin, dental, wound, stomach, nasal, toenail and other infections which are amenable to effective light delivery.
Development and comparison of two devices for treatment of onychomycosis by photodynamic therapy
Journal of biomedical optics, 2015
Onychomycosis is the most common nail disorder. The treatment for this type of infection is one of the main difficult ones in clinical practice, due to the fact that the nails are nonvascularized structures, which compromise the penetration of drugs delivered systemically and favor slow nail growth. We present two devices based on light-emitting diode arrays as light sources for the treatment of onychomycosis by photodynamic therapy (PDT). PDT is an emerging technique that uses a photosensitizer (PS) activated by light in the presence of oxygen. The PS absorbs energy from light and transfers it to oxygen, producing reactive oxygen species such as hydroxyl radicals, superoxide, and singlet oxygen which inactivate fungi and bacteria. Our proposal is the use of a portable and secure light source device in patients with onychomycosis. Additional advantages are the low cost involved, the possibility of topical treatment rather than systemic and the simplicity of operation. These advantag...
Optics and Photonics Journal, 2013
Fungal and bacterial diseases, directly infecting various parts of body, have received much attention in recent years. Bacterial infections, such as Tinea Pedis, Pityriasis versicolor and Mycetoma can secondarily occur in superficial fungal damaged skin. They often occur in immune compromised individuals including diabetics and patients with peripheral arterial diseases. Mycetoma infections can travel through the bloodstream affecting different organs. In this paper, we investigate the photo-inactivation of the pathogens causing Tinea Pedis, Pityriasis versicolor, and Mycetoma infections in three therapy resistant patients without photosensitizing drugs. We have used a combination of visible to near-infrared (VIS/NIR) laser beams in association with blue (B), red (R) and ultraviolet (UV) light emitted diodes (LEDs) with incident doses of 0.63-21.43 J/cm 2. These beams have minimum side effects on the normal part of the skin. According to the physicians' assessments, all case study patients achieved an observable progress such as decreases in inflammatory lesions, rapid process of wound healing and scars improvements. Side effects such as inflammation, crusting, or hypopigmentation were not observed. The presented irradiation protocol may be a valuable complementary treatment for patients suffering from fungal and bacterial skin infections.
Light treatments of nail fungal infections
Journal of biophotonics, 2017
Nail fungal infections are notoriously persistent and difficult to treat which can lead to severe health impacts, particularly in the immunocompromized. Current antifungal treatments, including systemic and topical drugs, are prolonged and do not effectively provide a complete cure. Severe side effects are also associated with systemic antifungals, such as hepatotoxicity. Light treatments of onychomycosis are an emerging therapy that has localized photodynamic, photothermal or photoablative action. These treatments have shown to be an effective alternative to traditional antifungal remedies with comparable or better cure rates achieved in shorter times and without systemic side effects. This report reviews significant clinical and experimental studies in the field, highlighting mechanisms of action and major effects related to light therapy; in particular, the impact of light on fungal genetics.
Effects of different infection control methods on the intensity output of LED Light-Curing Units
King Saud University Journal of Dental Sciences, 2013
Objective: To evaluate the effect of two different infection control techniques on the irradiance value output of LED curing units. Methods: Two different infection control techniques were involved in this investigation: (1) autoclaving and (2) disinfectant with a clear barrier. A high-power LED (Elipar S10, 3 M, Neuss, Germany) was used as the curing unit. Light irradiance values (mW/cm 2) of each light tip were measured by a calibrated spectral device (PS-MARC [Patient Simulator-Managing Accurate Resin Curing] BlueLight Analytic Inc., Halifax, Nova Scotia, Canada). For each group, 5 new curing tips were involved and a total of 25 cycles were performed. For the autoclave group, each of the 5 curing tips was sterilized with an autoclave cycle (15 min). In the second group, the 5 tested tips were wiped with a disinfectant solution (MinutenSpray, APMD GmbH, Munich, Germany) and then covered with a clear commercial disposable barrier (Disposa-Shield, Dentsply, USA). The statistical analysis involved using the t-test and the Tukey test. Results: Analysis of the data showed reductions of irradiance values in both groups compared with the baseline values. The group with autoclaved curing tips had a lower value compared with the disinfectant/barrier tips group. There were statistically significant differences between the tested groups (P < 0.05). Conclusion: The quality of the tested LCU was reduced when either of the above infection control techniques was used. Clinicians are recommended to monitor their LCU by applying the same infection control methods on light tips when testing its irradiance value.
Alternative Uv Light Sources for Surface Disinfection
2021
Mercury UV-C light sources are long known to be efficient for microbial inactivation and have been widely used. At the same time, the radiation, if used in inappropriate doses and spectral regimes, can also cause harmful effects to human tissue. The aim of the study was to evaluate the applicability of the novel UV light sources from thallium – antimony at different UV-C. For the research specially made light sources were produced. The influence of UV-C radiation in the range of 200 280 nm was tested on Gramnegative bacterium Escherichia coli, both with mercury and thallium. More than 99.99 % inactivation of E. coli cells was obtained after 10 min contact time for thallium – antimony UV-C light source, demonstrating the potential of the produced lamps.
Application of ultraviolet light sources for in vivo disinfection
Japanese Journal of Applied Physics, 2021
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Relevant factors affecting microbial surface decontamination by pulsed light
International Journal of Food Microbiology, 2012
Pulsed Light (PL) uses intense flashes of white light rich in ultraviolet (UV) light for decontamination. A logreduction higher than 5 was obtained in one flash and at fluences lower than 1.8 J/cm 2 on spores of a range of spore-forming bacteria, of vegetative cells of non-spore-forming bacteria and on yeasts spread on agar media. Vegetative cells were more sensitive than spores. The inactivation by PL of Bacillus subtilis, B. atrophaeus, B. cereus, Geobacillus stearothermophilus, and Aspergillus niger spores sprayed on polystyrene was similar. The inactivation by PL of B. subtilis and A. niger spores sprayed on glass was slightly lower than on polystyrene. No alteration of the spore structures was detected by scanning electron microscopy for both PL treated B. subtilis and A. niger spores. The inactivation of spores of B. subtilis, B. atrophaeus, B. cereus and B. pumilus by PL or by continuous UV-C at identical fluences was not different, and was much higher by PL for A. niger spores. The increase in the input voltage of the lamps (which also increases the UV-C %) resulted in a higher inactivation. There was no correlation between the resistance to heat and the resistance to PL. The relative effect of UV-C radiations and light thermal energy on PL inactivation was discussed.