Synergistic antimicrobial interaction between honey and phage against Escherichia coli biofilms

Abstract

Chronic wounds that take months, years or may even never heal present a major biological and financial problem on both individual patients and the broader health system. Chronic wounds afford a hostile environment of damaged tissues that allow bacterial proliferation and further wound colonization. Wound colonization by bacterial biofilms is one of the main obstacles of chronic wounds healing. Biofilms are structured communities of bacterial cells enclosed in a self-produced polymeric matrix and adhered to an inert or living surface. Escherichia coli is among the most common colonizers of infected wounds and it is a prolific biofilm former. Living in biofilm communities, cells are protected, become more difficult to control and eradicate, and less susceptible to antibiotic therapy. Due to the vast increase of antibiotic resistant bacteria, there is a renewed interestin pre-antibiotic therapies. Years before the discovery of modern antibiotics, bacteriophages(phages) that are bacterial viruses, and beehive products such as honey were extensively used for their antimicrobial properties. Phages, are the natural bacterial enemies and have proven efficacy towards antibiotic-resistant bacteria, have self-replicating nature, do not interfere with the commensal flora and many studies acknowledge that phages can destroy, tovarying extent, mono and mixed biofilm populations. Honey, on the other hand, has a broad spectrum antibacterial activity against bacteria and its high viscosity provides a protective barrier against infections being suitable for skincare, promoting the wound healing, tissue regeneration and anti-inflammatory process. This work presents insights into the proceedings triggering E.coli biofilm control with phage, two Portuguese(PT) honeys and their combination, achieved through standard antimicrobial activity assays, zeta potential and flow cytometry studies and further visual insights sought by SEM and TEM microscopy.