Design of Sponge-like Chitosan Wound Dressing with Immobilized Bacteriophages for Promoting Healing of Bacterially Infected Wounds

Application of wound dressings loaded with antimicrobial agents is considered a viable option to reduce wound bacterial colonization and prevent infection, in order to improve the healing process. In this study, we developed an easy-produced chitosan sponge-like wound dressing containing a broad-host spectrum Escherichia phage BIM BV-67 as an antimicrobial component. This novel dressing was entirely composed of biologically safe and biocompatible materials, had a porous structure, was biodegradable, and exhibited a high swelling capacity. Atomic force microscopy of model layer-by-layer modified planar surfaces and scanning electron microscopy of chitosan sponges showed a non-oriented adsorption and low density of phage particles on chitosan surface. However, immobilized Escherichia phage BIM BV-67 maintained its infectivity and lytic activity. Phage-loaded chitosan sponges effectively inhibited growth of E. coli BIM B-984 G in both qualitative (agar diffusion) and quantitative (suspension) in vitro assays. Moreover, the dressings with phage retained bactericidal activity for 12 weeks when stored at 4 °C. Furthermore, in vivo testing showed that topical application of phage-loaded chitosan sponges significantly reduced the number of E. coli BIM B-984 G cells in the wound and resulted in accelerated wound surface regeneration in infected rats compared to the use of pure sponges and no treatment. Based on these promising results, developed technology has potential as a platform for producing topical dressings with immobilized phages active against wide range of wound-infecting pathogens. In turn, this could promote the application of phage therapy in wound management.