Photodynamic inactivation (PDI) is considered to be an effective method of prevention of postoperative complications of urolithiasis. The present study shows a complex approach to assess the efficacy of PDI of drug resistant bacteria associated with renal calculi. Bacterial strains associated with renal calculi were isolated and identified using standard methods of bacteriological analysis and tested for drug resistance to 10 antibiotics by the disco-diffusion method. Uropathogenic bacterial strains present in 78.7 ± 5.2% of the infected samples from the total number of analyzed calculi. The most frequent representatives belonged to the genera Staphylococcus, Escherichia, and Enterococcus. All tested strains showed high antibiotic resistance. Representatives of the most common bacterial genera in the calculi were used as models for the selection of PD exposure modes. It was found that the maximum time of photosensitizer accumulation depends on the structure of the bacterial cell wall: 30 min for Gram-negative strains and 60 min for Gram-positive ones. Optimal modes of PD exposure to antibiotic-resistant uropathogenic microorganisms were selected: 50 µg/mL Fotoditazin and 150 mW laser power. The maximal bactericidal activity of PDI against uropathogenic microorganisms was shown for Enterococcus faecalis, and Staphylococcus aureus. The bacteriostatic effect was found against Escherichia coli and Proteus mirabilis.

Antimicrobial photodynamic therapy (aPDT) was demonstrated to be effective against various species of Gram-positive bacteria. However, the complex structure of a Gram-negative bacteria envelope limits the application of aPDT. Thus, the goal of this study was to improve the efficiency of antimicrobial photodynamic therapy with Fotoditazin against uropathogenic Gram-negative bacteria. The non-ionic detergent Triton X-100 and emulsifier Tween 80 were tested. The effect of extracellular photosensitizer on aPDT efficacy was analyzed. Moreover, the irradiation regime was optimized in terms of the output power and emitting mode. It was found that Triton X-100 at 10% vol enhanced the efficacy of aPDT of E. coli up to 52%. The subsequent observation demonstrated that, when the photosensitizer was removed from the extracellular space, the efficacy of aPDT on various Gram-negative species decreased dramatically. As for the irradiation mode, an increase in the laser output power led to an increase in the aPDT efficacy. The pulsed irradiation mode did not affect the aPDT efficacy. Thus, in order to achieve optimal aPDT efficacy, bacteria should be irradiated at 450-mW output power in the presence of Triton X-100 and a photosensitizer in the extracellular environment. However, it should be noted that the efficacy of aPDT of K. pneumoniae was significantly lower than for other species. The developed aPDT technique may be effective in a native environment of uropathogenic microorganisms.

Due to the prevalence of postoperative complications in the treatment of urolithiasis, the study of the contamination of urinary calculi and the potential pathogenicity of isolated bacteria is of great importance in laboratory diagnostic practice. It has been shown that uropathogenic bacteria are found in the composition of urinary stones in 65±7.1% of cases, mainly representatives of the Enterobacteriaceae and Staphylococcaceae families. Bacteria of the generas Escherichia, Enterococcus, Staphylococcus were most frequently detected. The analysis of biofilm activity and antibiotic resistance in 50 uropathogenic strains was carried out. It was shown that all the studied strains were resistant to at least two tested drugs, and the average value of the multiple resistance index was 0.51. When cultured on nutrient agar with Congo red, it was shown that more than half of the tested strains have high biofilm activity and about 80% potential for biofilm formation. The greatest biofilm activity was observed in bacteria of the generas Escherichia, Klebsiella, Enterobacter, Staphylococcus.

The introduction of technologically advanced methods of lithotripsy into medical practice changes the nature of postoperative complications. Among them, the main complications are inflammatory infections. This largely determines the search for new, improved methods of stone fragmentation avoiding small stone fragments and dissemination of the pelvicalyceal system of the kidney with stoneassociated infection. The authors have developed a method for controlled stone fragmentation using a continuous-wave diode laser with a hot-spot effect at the optical fiber end.The aim of the study was to evaluate the efficacy of controlled urinary stone fragmentation using a continuous-wave diode laser with a highly heated distal end of the optical fiber light guide as a method of preventing inflammatory infections in clinical practice.Materials and Methods. We analyzed 1666 case histories of urolithiasis patients who underwent percutaneous nephrolithotripsy/ nephrolithoextraction and contact ureterolithotripsy/ureteroextraction, we also performed a prospective analysis of complications based on the Clavien-Dindo classification in 90 patients who underwent fine fragmentation of stones with various lithotripters: ultrasonic, pneumatic, and holmium laser. The method of controlled stone fragmentation by a diode laser with a hot-spot effect was tested on postoperative samples of 26 renal calculi. For the first time in clinical practice, this method was tested in the bladder cavity (n=10).Results. In the percutaneous nephrolithotripsy group, postoperative infectious and inflammatory complications occurred in 34.1% of cases, in the percutaneous nephrolithoextraction group -in 24.6%, in the contact ureterolithotripsy group -in 7.8%, in the ureterolithoextraction group -in 2.5%. The analysis made it possible to identify factors promoting the development of infectious and inflammatory complications. For the first time in clinical practice, there were successfully performed ten operations of stone fragmentation using a continuous-wave diode laser with a hot-spot effect. Controlled coarse fragmentation of stones providing the possibility to reduce the number of infectious and inflammatory complications was performed in the bladder as a model for testing the method.Conclusion. The method of laser-induced controlled coarse fragmentation of stones with a hot-spot effect, developed and tested in clinical practice, is promising for the prevention of infectious and inflammatory complications in patients with potentially infected stones since their fine fragmentation and, consequently, spread of stone-associated toxins and microflora within the urinary system is avoided.

Photodynamic inactivation (PDI) is an alternative to antibiotic therapy method for biocidal action against microorganisms, which can be used for lithotripsy and sanitation of the bladder cavities. Objective. Selection of parameters and application PDI against uropathogenic microorganisms. Materials and Methods. In this study we used bacterial strains isolated from urine samples of patients. Differentiation media and biochemical plates were used for identification of microorganisms. The sensitivity of uropathogenic microorganisms to PDI was studied on pure cultures and in native urine. The photosensitizer “Photoditazine” (50 µg/ml) was used in the work, as well as Triton X-100 (5 % vol.) was applying to increase the permeability of the cell wall of gram-negative microorganisms. The samples were irradiated by a medical laser device “Latus-K” with a wavelength of 662 nm. To assess the effectiveness of PDI, the values of the logarithmic decrease of colony-forming unit (CFU) of the microorganisms were calculated. Statistical analysis was made by Statistica 10.0 and Mann-Whitney criterion. Results. 50 strains of uropathogens belonging to 18 species were isolated from 36 samples of native urine. Among them, the most common were S. aureus, E. coli, P. aeruginosa, K. pneumoniae. The value of logarithmic decrease in CFU for gram-positive bacteria ranged from 5 to 6, which corresponds to inactivation 99.999-99.9999% of bacterial cells in a sample. For gram-negative strains, this value was slightly lower and ranged from 4 to 5.5, which, nevertheless, corresponds to inactivation 99.99-99.999% of CFU bacteria. The addition of Triton X-100 increase the efficiency from 46% to 99.99% for E. coli, from 99% to 99.99% for P. mirabilis, from 16% to 94% for K. pneumoniae and from 97% to 99.999% for P. aeruginosa. It should be noted that the PDI was affect microorganisms both in isolated pure cultures and in native urine. Conclusions. Photodynamic inactivation may be considered as an alternative to antibiotic therapy method of biocidal action against uropathogenic microorganisms.