Study of the effect of biogalvanic current on biofilm formation of multidrug-resistant clinical strains of opportunistic pathogens of wound infection

Abstract

Introduction.Standard antibiotic treatment is ineffective against infections associated with biofilms and multidrug-resistant pathogens. Purpose.To study the effect of low-intensity currents without external power sources on the biofilm-forming properties of multidrug-resistant pathogens responsible for infectious complications in combat wounds and burns. Materials and methods. The effect of biogalvanic current on the biofilm-forming properties was studied in relation to multidrug-resistant strains of Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa, isolated from infected combat-related shrapnel and blast wounds, as well as burns of various localizations. Clinical strain suspensions in saline solution and meat-peptone broth (MPB; ≈1.6 × 10⁹ CFU/mL) were pre-exposed to low-intensity currents (46-50 μA in saline and 54-60 μA in MPB) for 48 hours. Biofilm formation was assessed using Christensen’s method, which is based on microorganism adhesion to the surface of a plastic microplate, followed by fixation, staining with crystal violet, and spectrophotometric analysis of the dye dissolved in alcohol. Optical density (OD) was measured at a wavelength of 620 nm. Results. Exposure to galvanic current without external power sources induced a bioelectric effect, resulting in a reduction in the biofilm-forming properties of multidrug-resistant clinical strains of S. aureus, A. baumannii, and P. aeruginosa. The decrease was observed both in nutrient medium conditions (by 28.26%, 24.82%, and 11.89%, respectively) and in saline solution (by 33.18%, 28.0%, and 16.31%, respectively). A statistically significant reduction in biofilm formation intensity was observed for S. aureus and A. baumannii after exposure to current in MPB, with OD values 1.38-fold (p < 0.001) and 1.33-fold (p = 0.01) lower than the control, respectively. The optical density values were 0.223±0.008 OD units and 0.238±0.010 OD units compared to control values of 0.311±0.019 OD units and 0.317±0.019 OD units. Under the influence of low-intensity current in isotonic solution, the indicators characterizing the biofilm-forming ability of clinical strains of S. aureus, A. baumannii, and P. aeruginosa were statistically significantly lower by 1.19–1.49 times, measuring 0.200±0.013 OD (p = 0.05) and 0.364±0.020 OD (p < 0.05), respectively, compared to the control (0.304±0.020 OD, 0.286±0.021 OD, and 0.435±0.027 OD, respectively). Conclusions. Continuous exposure to low-intensity current without external power sources in isotonic solution and nutrient meat-peptone broth reduces the biofilm-forming properties of clinical strains of S. aureus, A. baumannii, and P. aeruginosa by 11.89–33.18%, indicating additional therapeutic potential of biogalvanic current in treating infectious complications caused by biofilm-forming multidrug-resistant microorganisms