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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.

Annotation. The development and rapid pace of the spread of resistance to antimicrobial agents predetermines the search for new methods of counteracting pathogenic and conditionally pathogenic microorganisms. In this context, studies of the antimicrobial activity of newly synthesized chemicals, which in the future can be considered as candidates for antiseptic and disinfectants, are relevant. The aim of the work was to determine the antimicrobial activity of new ionic associates based on the surface-active cetylpyridinium cation with respect to certain opportunistic microorganisms. The antimicrobial activity of four ionic associates based on the cetylpyridinium cation with respect to clinical isolates of E. coli, P. vulgaris, K. pneumonia, P. aeruginosa, S. aureus, as well as the collection test strains of S. aureus ATCC 25923, E. coli ATCC 29522 and P. aeruginosa ATCC 27853 was studied. Screening studies were performed by the disk diffusion method. With substances that showed an antimicrobial effect, quantitative studies were carried out by the method of serial macro-dilutions in a liquid nutrient media. Screening studies revealed the antibacterial activity of the substances against E. coli ATCC 25923, E. coli (clinical isolate), P. vulgaris and K. pneumonia. With these microorganisms quantitative studies were carried out with the determination of the minimum inhibitory and minimum bactericidal concentrations. The most pronounced antimicrobial activity for the investigated microflora was shown by tetraphenylborate and cetylpyridinium perchlorate. The MIC and MBC values of these substances ranged between 1.625–3.125 mmol / L and 3.125–12.5 mmol / L, respectively. The studied associates showed high antimicrobial activity against representatives of the Enterobacteriaceae family in in vitro studies. Promising is the further study of the effect of the counter-anion associates of cationic surfactants on the biofilm formation of conditionally pathogenic microorganisms.

The spread of resistant to antimicrobial agents strains of opportunistic microorganisms causes the search for new ways of struggle with them. Among these ways, special attention is drawn to the use of physical factors, in particular, different types of radiation, with potential antimicrobial activity. Purpose: to investigate the direct effect of the PILER wave length line on the growth rate of S.aureus ATCC 25923 and P.aeruginosa ATCC 27853 on solid nutrient media. The influence of PILER (Polarized Polychromatic Incoherent Low Energy Radiation) on various wavelengths on the growth intensity of the collection test- strains of S.aureus ATCC 25923 and P.aeruginosa ATCC 27853 on solid nonselective nutrient media (NA) was investigated. The results were determined by counting the number of bacterial colonies on the dishes and compared with control – similar unirradiated cultures. The effect of PILER of different wavelengths and exposures (5, 10, 15 and 20 min) was investigated by separate series. PILER light source – Med All Bioptron light therapy system by Zepter Group. The obtained results testify to the significant influence of PILER radiation on the intensity of the growth of research objects. The degree of influence depended on the duration of irradiation and showed insignificant stimulation of the growth of bacteria in 5–10-minute exposures and expressed bactericidal and bacteriostatic effect at exposure for 20 minutes. The 20-minute exposure PILER on the S.aureus 25923 strain resulted in a decrease of the number of bacterial colonies by 37–65% compared to control, P.aeruginosa 27853 – by 58–81% compared to control. PILER has a significant modulator effect on the growth of the examined conditionally pathogenic microorganisms on solid nutrient media. The degree of this effect depends on the radiation parameters, in particular on the dose density and the wavelength of light, and at exposures of 20 minutes is manifested in marked bactericidal and bacteriostatic effects on microorganisms.