Intraoperative application of photodynamic therapy as a method of inactivation of uropathogenic flora (pilot study)

BACKGROUND: The predictor of experimental work on animals on the use of antimicrobial photodynamic therapy to neutralize antibiotic-resistant strains of microorganisms was the analysis of the microbial landscape of patients’ urine and swabbings from the working surfaces of objects of the urological hospital.

AIM: The aim of the study is was to study the possibility of intraoperative photodynamic inactivation of uropathogenic microorganisms.

MATERIALS AND METHODS: Analysis of the species specificity of microorganisms was performed based on the results of urine cultures of patients in a urological hospital and external introduction infections over the past 10 years. The experimental part of the work was carried out on 7 animals (pigs). Photodynamic therapy was performed intraoperatively by local injection into the animals’ renal pelvis of the photosensitizer photoditazine in physiological solution with the addition of the nonionic surfactant Triton X-100 to a concentration of 10%. To study the damaging effect on the tissue of the pelvis, a histological study of animal kidneys was performed. To assess the biocidal effect on uropathogenic bacteria introduced into the renal pelvis, we used suspensions of daily test cultures (1 × 10⁸ CFU/ml) of microorganisms most often found in the stones of patients with urolithiasis.

RESULTS: Escherichia coli, Enterobacter cloacae, Staphylococcus epidermidis, Enterococcus faecalis и Klebsiella pneumonia were the most frequently present in urine over 10 years. The safety of using photodynamic therapy in the renal pelvis of animals was comprehensively studied. It was found that the accumulation of the photosensitizer by the cells of the lining epithelium of the renal pelvis did not occur; the photosensitizer solution in the renal pelvis was not heated during photodynamic therapy. Histological examination established the absence of significant damage to the epithelium of the renal pelvis of the animals under the influence of various irradiation modes. The analysis of the bactericidal activity of the method used showed that photodynamic therapy leads to the death of 99.9% of E. coli and 99% of S. aureus.

CONCLUSIONS: The experiment established that intraoperative photodynamic therapy is an effective and safe method of inactivating uropathogenic microorganisms, which allows it to be considered as an alternative to antibiotic therapy.