Modified photodynamic therapy of purulent wounds (experimental study)

Abstract

Introduction. The widespread use of antibiotics that have a mutagenic effect on the microflora causes a
change in the etiological structure of purulent infection, as well as the biological properties of the microbial cell
with the appearance of antibiotic-resistant strains of microorganisms. The consequence of this was a decrease
in the effectiveness of antibiotic therapy, traditionally prescribed local treatment of wounds and amid growing
allergization of the population. One of the promising methods of combating the antibiotic resistance of microorganisms
is antimicrobial photodynamic therapy.
Purpose. An experimental study is devoted to studying the results of the treatment of purulent wounds in the
first phase of the wound process using modified photodynamic therapy depending on the species of the pathogen.
Materials and methods. The study was conducted on 18 white Wistar male rats, divided into three
groups depending on the type of sanation of purulent wounds (6 animals in each series). In the control group,
wound treatment was performed by reorganization with chlorhexidine, in the second experimental group, photodynamic
therapy sessions were performed, in the third experimental group, the photosensitizer was modified
with chitosan. In dynamics, we studied the microbial contamination of wounds, the lethality of animals, and
also performed histological and morphometric studies.
Results. With regard to gram-negative rods, the use of «Photolon» as a photosensitizer led to a significant
reduction in bacterial contamination: in the crops, the number of germinated colonies was less than 10 bacteria/
ml, which suggests the selectivity of this type of photochemical effect with respect to gram-negative flora.
Conclusions. Modified PDT was effective against gram-negative bacilli (plating decreased from 3.70 ± 0.05 × 104
(log CFU/ml = 4.5682) to 2.90 ± 0.05 × 104 (log CFU/ml = 4.4623) and with respect to gram-positive pathogens:
the number of CFU/ml after the second session was < 1.0 ± 0.05 (log CFU/ml = 1). Histological and morphometric
studies showed the advantages of modified PDT compared to traditional treatment of purulent wounds.