Introduction: Candida species are responsible for about 80% of hospital fungal infections. Non-thermal plasmas operated at atmospheric pressure are increasingly used as an alternative to existing antimicrobial strategy. This work investigates the action of post-discharge region of a non-thermal atmospheric plasma jet, generated by a gliding arc reactor, on biofilms of standard strain of Candida albicans grown on polyurethane substrate. Methods: Samples were divided into three groups: (i) non-treated; (ii) treated with argon plasma, and (iii) treated with argon plus air plasma. Subsequently to plasma treatment, counting of colony-forming units (CFU/ml) and cell viability tests were performed. In addition, the surface morphology of the samples was evaluated by scanning electron microscopy (SEM) and optical profilometry (OP). Results: Reduction in CFU/ml of 85% and 88.1% were observed in groups ii and iii, respectively. Cell viability after treatment also showed reduction of 33% in group ii and 8% in group iii, in comparison with group i (100%). The SEM images allow observation of the effect of plasma chemistry on biofilm structure, and OP images showed a reduction of its surface roughness, which suggests a possible loss of biofilm mass. Conclusion: The treatment in post-discharge region and the chemistries of plasma jet tested in this work were effective in controlling Candida albicans biofilm contamination. Finally, it was evidenced that argon plus air plasma was the most efficient to reduce cell viability.
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 gram-negative 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.
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