In vitro evaluation of drug release and antibacterial activity of a silver-loaded wound dressing coated with a multilayer system

The goal of the study was to elaborate an antibacterial silver wound dressing covered by a protective coating that would prevent silver diffusion toward skin without losing its biocide properties. Therefore, non woven polyethyleneterephtalate (PET) textiles were pre-treated by two types of polysaccharides - chitosan and cyclodextrin - both crosslinked with citric acid by a pad/dry/cure process. Both types of resulting thermofixed textiles carrying the citrate crosslinks were then impregnated in silver solution followed by a thermal treatment and were finally coated by Layer-by-Layer (L-b-L) deposition of a polyelectrolyte multilayer (PEM) film consisting of anionic water-soluble poly-cyclodextrin and cationic chitosan. The influence of the process parameters was investigated in terms of silver adsorption capacity, PEM system build-up, silver kinetics of release and antibacterial activity. We demonstrate i) the utility of the intermediate thermal treatment step in the reduction of silver leakage in the polyelectrolyte solutions used in the L-b-L process, ii) that silver adsorption on the preliminary thermofixed layers did not affect the PEM system build-up, iii) the slowing down of silver release kinetic thanks to the PEM coating, iv) the preservation of the antibacterial activity despite the PEM coating.

Bacteriophages Targeting Adherent Invasive Escherichia coli Strains as a Promising New Treatment for Crohn's Disease

BACKGROUND AND AIMS

Adherent invasive Escherichia coli [AIEC] are abnormally predominant on the ileal mucosa of Crohn's disease [CD] patients. They bind to the CEACAM6 receptor expressed on the surface of epithelial cells. We aimed to assess the potential of bacteriophages, viruses infecting bacteria, to decrease the levels of AIEC bacteria associated with the intestinal mucosa.

METHODS

We combined ex vivo and in vivo experiments with murine and human intestinal samples to quantify the ability of virulent bacteriophages to target the prototype AIEC strain LF82.

RESULTS

We found that three virulent bacteriophages were able to replicate in ileal, caecal and colonic sections and faeces homogenates from murine gut samples colonised with the prototype AIEC strain LF82. A single day of per os treatment with the three bacteriophages cocktail given to LF82-colonised CEABAC10 transgenic mice, expressing the human CEACAM6 receptor for AIEC, decreased significantly the number of AIEC in faeces and in the adherent flora of intestinal sections. In addition, a single dose of the cocktail reduced dextran sodium sulphate-induced colitis symptoms on conventional mice colonised with the strain LF82 over a 2-week period. The cocktail targeted also LF82 bacteria in homogenates of ileal biopsies taken from CD patients.

CONCLUSIONS

These findings demonstrate that bacteriophages are a new treatment option for targeting AIEC in CD patients and represent a strong basis for a clinical trial evaluation.