## Materials and Methods
### Studies In Vitro  
Studies of the bactericidal and wound-healing effectiveness of the Zarnitsa-A apparatus were carried out at the Izmerov Research Institute of Occupational Health. The purpose of the ongoing microbiological studies was to evaluate the in vitro bactericidal action of the \"Zarnitsa-A\" apparatus in relation to clinically significant microorganisms (MOs). The following types of MOs (and their strains) were selected as research objects:  
* Gram-negative bacteria: _Escherichia coli_ (M-17 (O2:H6)) and _Pseudomonas aeruginosa_ (ATCC 9027/NCTC 12924);
* Gram-positive bacteria: _Staphylococcus aureus_ (ATCC 6538-P/FDA 209-P) and _Streptococcus pyogenes_ (ATCC 12344/NCTC 8198). The MO strains were obtained from the State Collection of Pathogenic Microorganisms and Cell Cultures (\"SCPM--Obolensk\") and had a BSL-1 biosafety level. The selected strains were not drug-resistant, except for _Staphylococcus aureus_, which was resistant to the antibiotic novobiocin. Preparation of the control-strain MOs and the initial suspension was carried out in the following way. We took a pure culture of specific bacteria and sowed it on mown meat-pentone agar (MPA) to obtain a daily culture. From the daily agar culture of the control-strain MOs, a suspension was prepared in physiological saline. We prepared the suspension with a given concentration of cells, using the optical turbidity standard 0.5 according to McFarland. The Densi-La-Meter II device (manufactured by Erba Lachema, Czech Republic) was used to determine the turbidity of the bacterial suspension. To more accurately determine the initial concentration of MOs in the suspension intended for the experiment, serial dilutions of the resulting suspension were performed using the tenfold dilution method. In the experiments, the following was carried out: (1) positive control (1.0 cm\({}^{3}\) of inoculum was taken from each dilution with an automatic dispenser and transferred to the surface of the agar medium)--this controlled the prepared suspension and further helped to calculate the results; (2) negative control (without inoculation)--this controlled the sterility of nutrient media, utensils, and instruments. When preparing the experimental Petri dishes, 1.0 cm\({}^{3}\) of seed material was evenly distributed with a spatula over the surface of the agar, 0.5...1 cm away from the side walls of the Petri dish, which was necessary to exclude possible parietal effects. Petri dishes90 mm in diameter were used in the experiments; accordingly, the area of the sown surface was S \(\approx\) 50 cm\({}^{2}\). The initial density of MOs in the suspensions varied in a range of 10\({}^{6}\) to 4.10\({}^{8}\) CFU/cm\({}^{3}\), which provided the initial surface contamination of the agar medium: \(N_{50}=N_{0}\cdot\frac{V_{0}}{S}=2\cdot 10^{4}\ldots 8\cdot 10^{6}\) CFU/cm\({}^{2}\), where \(N_{50}\) refers to the initial surface contamination of the agar medium; \(N_{0}\) is the initial density of MOs in the suspensions; \(V_{0}=1\) cm\({}^{3}\)--volume of the inoculated aliquot; \(S\)--the area of the contaminated surface of the agar medium. MPA was used as a nutrient medium on which MOs were inoculated in all experiments. For each irradiation mode, three Petri dishes were prepared to ensure a 3-fold repetition of measurements. Experimental Petri dishes with the inoculated culture (after drying at room temperature for 30 min) were irradiated using the \"Zarnitsa-A\" apparatus. The irradiator of the apparatus was fixed in a special stand, which made it possible to adjust the distance from the irradiator to the irradiated object. Cups with bacterial inoculations (control and workers after irradiation) were incubated in a thermostat at a temperature of (37 \(\pm\) 1) \({}^{\circ}\)C for 24 h. After that, the formed colonies were counted. Most of the experiments were performed at a distance of the irradiator L = 10 cm from the contaminated surface to the end plane.