Synergy of action of antimicrobial peptides PG-1 and ChBac3.4 with antiseptics against antibiotic-resistant bacteria

Abstract

We investigated the combined effects of antimicrobial peptides PG-1 and ChBac3.4 with antiseptics (sodium hypochlorite, dioxidine, prontosan, poviargolum, and etidronic acid) to identify combinations that display synergistic antimicrobial activity against antibiotic-resistant bacteria. We used the checker-board titration method to calculate fractional inhibitory concentration indices, and based on the indices the type of combined action was determined. The combined effect on the metabolic activity of bacteria was evaluated using the fluorescent marker resazurin, and the effect on the permeability of bacterial membranes for chromogenic markers was studied spectrophotometrically. The combined hemolytic activity of the combinations was investigated. Sodium hypochlorite was shown to be antagonistic with both antimicrobial peptides. With other antiseptics, combined action was characterized by additivity or synergy. Synergy was most pronounced with the preparation of highly dispersed silver poviargolum. Antiseptics accelerate the development of the antimicrobial effect of antimicrobial peptides but do not significantly affect the dynamics of the membranolytic action of antimicrobial peptides on bacterial cells. Synergy of hemolytic activity is rare. Thus, the combined use of antimicrobial peptides and antiseptics is promising for combating antibiotic-resistant bacteria and can be used to reduce the toxic effects of these compounds.