In-vivo effects of antibacterial polyelectrolyte multilayer coatings functionalized by bacteriophages for metallic medical implants

Implant-associated-infections against the background of multi-drug-resistance cause severe complications in orthopedic and trauma surgery and burden global healthcare. Equipment of implants with antibacterial coatings loaded by lytic bacteriophages (PHAG) are seen promising in this respect. Here, we report antibacterial polyelectrolyte multilayer (PEM) coatings functionalized by PHAG, which were deposited at model substrates and metallic implants by consecutive adsorption from solutions of poly-l-lactide-modified hyaluronic acid (DAC), ethylenediamino-cellulose (EDAC) or poly(ethyleneimine) (PEI) according to layer-by-layer technique. PHAG against Staphylococcus aureus (S. aureus) bacteria were bound at five- and six-layered PEM coatings of PEI/DAC or EDAC/DAC, respectively. PEM deposition and PHAG interaction were studied by FTIR and SFM. In-vivo antibacterial properties of PHAG/PEM coatings against S. aureus bacteria were evaluated using Galleria mellonella (G. mellonella) larvae infection model. PEM coatings of EDAC/DAC revealed far higher deposited polymer amounts compared to PEI/DAC and far more PHAG were bound at thicker EDAC/DAC compared to thinner PEI/DAC coatings. Higher relative released PHAG amount (40-80%) was found for thinner PEI/DAC coatings, while lower one (10-20%) for thicker EDAC/DAC coatings. In-vivo studies revealed survival rates >80% of uninfected G. mellonella larvae treated with uncoated and PEM/PHAG coated metallic implants, indicating biocompatibility of the used materials. Infected G. mellonella larvae showed survival rates of 33%-43% for metallic implants with PEM/PHAG coatings of EDAC/DAC, which were higher with statistical significance compared to uncoated controls (13%), indicating excellent antibacterial properties.