The dissertation is devoted to the research of the efficiency of the combined use of silver nanoparticles and low–frequency ultrasound in the treatment of purulent surgical infection.
Surgical infections of the skin and soft tissues now occupy one of the first places in the structure of surgical morbidity and account for 30-45 %. Despite adherence to the principles of asepsis and antiseptics, the development of minimally invasive technologies, widespread use of antibacterial drugs, the number of patients with wound infection does not tend to decrease, and the incidence of surgical infection remains consistently high and ranks third in nosocomial infections.
The aim of the study was the experimental substantiation of the combined use of silver nanoparticles and low-frequency ultrasound in the treatment of purulent surgical infection.
According to the set tasks the following research methods were used: general clinical, planimetric, morphometric, bacteriological, histological, cytological, statistical, inductively coupled plasma atomic emission spectrometry, transmission electron microscopy, atomic absorption spectrometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy.
Synthesized silver nanoparticles, 25-60 nm sizes, have high antimicrobial activity against purulent surgical infections (S. aureus, S. pyogenes, E. coli, K. pneumoniae, P. aeruginosa, P. vulgaris та C. albicans) in-vitro at concentrations from 12.5 μg/ml to 50.0 μg/ml. The combined use of silver nanoparticles and low-frequency ultrasound (26.5 ± 1.98 kHz) allows to significantly enhance the antimicrobial activity of silver nanoparticles (minimally inhibiting and bactericidal concentrations decrease to 0.012 – 0.78 μg/ml and 0.05 – 1.6 μg/ml, respectively), reduce the rate of elimination of pathogens and improve the antibiofilm activity of silver nanoparticles.
No cytotoxic effect of silver nanoparticles was observed in dermal fibroblast cell culture after 72 h at concentrations below 3.2 μg/ml and after 24 h at silver nanoparticles concentrations below 6.4 μg/ml. The effective antimicrobial concentration of silver nanoparticles in combination with low-frequency ultrasound (26.5 ± 1.98 kHz) did not exceed the allowable cytotoxic values, which allows the use of silver nanoparticles in the treatment of purulent surgical infection at concentrations below 1.6 μg/ml.
The results of an experimental study in laboratory rats in-vivo indicate a positive dynamics of healing and acceleration of all phases of the wound process of acute purulent wounds and purulent wounds that do not heal for a long time with the combined use of silver nanoparticles and low-frequency ultrasound.
The combined use of silver nanoparticles and low-frequency ultrasound (26.5 ± 1.98 kHz) in the treatment of acute purulent wounds can accelerate healing by faster cleansing of wounds from purulent-necrotic tissues, better elimination of bacterial microflora, faster granulation, and epithelialization, compared with the treatment of 0.05 % chlorhexidine solution, monotherapy with silver nanoparticles or low-frequency ultrasound. Complete closure of wound defects of acute purulent wounds occurred 11.3 days faster (p ≤ 0.0001), compared with the treatment of chlorhexidine solution; 5.1 days faster (p < 0.05), compared with monotherapy of silver nanoparticles; and 2.2 days faster (p < 0.05), compared with low-frequency ultrasound monotherapy.
In the treatment of purulent experimental wounds that do not heal for a long time, with the combined use of silver nanoparticles and low-frequency ultrasound (26.5 ± 1.98 kHz), compared with 0.05 % chlorhexidine solution, silver nanoparticles or low-frequency ultrasound monotherapy, rapid ultrasound cleaning wounds from purulent-necrotic tissues, better elimination of bacterial microflora, faster granulation and epithelialization, and, as a consequence, faster wound healing. Complete epithelialization of purulent wounds that do not heal for a long time, with the combined use of silver nanoparticles and low-frequency ultrasound, occurred 6.9 days faster (p < 0.05), compared with treatment with 0.05 % solution of chlorhexidine; 2.9 days faster (p < 0.05) compared with silver nanoparticles monotherapy; and 4.2 days faster (p < 0.05), compared with low-frequency ultrasound monotherapy.
In the study of the rats' blood, the concentration of silver did not exceed the indicators of the control group and ranged from 0.06 μg/l to 0.16 μg/l. Local use of silver nanoparticles both as monotherapy and in combination with low-frequency ultrasound (26.5 ± 1.98 kHz) in the treatment of experimental acute purulent wounds and purulent wounds that do not heal for a long time does not have a systemic resorptive effect, does not cause increasing content of silver in the blood and in the tissues adjacent to the wound, but tends to accumulate silver nanoparticles directly on the surface of purulent wounds.
