Abstract
Resistance to antibiotics is considered as a global and unsolved problem in the branch of medicine. That is why the use of novel non-drug methods of treatment of bacterial and fungal infections is of great relevance. One of such methods is photodynamic treatment, which is a treatment procedure that uses light energy to activate a photosensitizing agent in the presence of oxygen. Due to the broad spectrum of action, the efficacy against antibiotic resistant cells and the lack of selection of photoresistant strains, antimicrobial photodynamic therapy compares favourably with traditional drug therapy, and has emerged in the clinical field as a potential alternative to antibiotics to treat microbial infections. In this article results of studies of the complex effect of methylene blue (0.1% aqueous solution) and LED radiation of the red-infrared spectrum as well as methylene blue and polarized incoherent low-energy radiation (PILER) with a red light filter on the growth rate of some opportunistic microorganisms on solid nutrient media are presented. Standardized suspensions of microorganisms were prepared for research with the subsequent determination of direct impact of polarized and non-polarized radiation (at duration of exposure of 5 min), photosensitizer, and also the set of these factors on growth of the studied microorganisms. The growth intensity of bacteria and yeast-like fungi was determined by the number of their colonies after reseeding on nutrient media in Petri dishes. The obtained data were compared with control groups, which were not influenced by any factors. The results indicate a significant antimicrobial effect of the combined action of different types of radiation and methylene blue on microorganisms, which was manifested in a reduction in the number of colonies by on average 35–45%, compared with the control groups. Comparing the effect of exposure when using LED and PILER light, we have noted its similarity. It is also worth noting a certain antimicrobial activity of 0.1% methylene blue solution on the studied strains, but this was much less pronounced than in the complex effect. The direct effect of both LED and PILER radiation with low duration of exposure caused the stimulation of the growth of the studied microorganisms with an increase in the number of their colonies on Petri dishes by 15–35%. Given the rapid growth of resistance to antimicrobial agents, the described technique can be used as an alternative to traditional antibiotic therapy for the treatment of purulent-inflammatory diseases of the skin and mucous membranes.
Highlights
The inevitable biological consequence of antibiotic therapy is the development of resistance of microorganisms, which requires the use of new generation drugs, stronger and more aggressive in relation to the human body (Melnychuk & Lychkovska, 2015)
The combined effect of red-infrared LED radiation (λ = 640 ± 30 and 880 ± 30, power density from a distance of 0–1 cm – 5.35 mW/cm2 at continuous irradiation) and polarized incoherent low-energy radiation valerij.pantyo@uzhnu.edu.ua (PILER) light with red light filter (λ ≈ 630 nm, power density on average 40 mW/cm2) and 0.1% aqueous solution of methylene blue on the growth rate on solid nutrient media of clinical isolates of S. aureus, E. coli, C. albicans and collection test strains of S. aureus ATCC 25923, E. coli ATCC 25922 and C. albicans ATCC 90028 was performed at the microbiological laboratory of the Department of Microbiology, Virology, Epidemiology with the Course of Infectious Diseases of Uzhhorod National University
Adding 0.1% solution of methylene blue caused decrease in the growth rate of the microflora by 16– 23% compared with the control
Summary
The inevitable biological consequence of antibiotic therapy is the development of resistance of microorganisms, which requires the use of new generation drugs, stronger and more aggressive in relation to the human body (Melnychuk & Lychkovska, 2015). It is important to search for new means to combat bacterial infections, among which a special place is occupied by both physical and chemical factors. These methods include phototherapy (Pantyo et al, 2017, 2018), antimicrobial photodynamic effects (Braun et al, 2008; Tavares et al, 2010; Kutsevlyak et al, 2014, 2015), ozone therapy (Melnychuk & Lychkovska, 2015), development of novel chemical entities with new mechanisms of action (Slivka et al, 2017), use of essential oils (Kryvtsova et al, 2019), antibiotic adjuvants (González-Bello, 2017) etc. Nondrug methods of combating infectious agents can, if not replace, limit the use of drugs, while affecting various parts of the pathological process, improving metabolic processes and activating the body's defense reactions (Melnychuk & Lychkovska, 2015; Bondar et al, 2016)
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