Antibacterial And Anti-Biofilm Activity Of Omega-3 Polyunsaturated Fatty Acids Against Periprosthetic Joint Infections-Isolated Multi-Drug Resistant Strains

Background: Implantable medical devices, such as prosthetics, catheters, and several other devices, have revolutionized medicine, but they increase the infection risk. In previous decades, commercially available antibiotics lost their activity against coagulase-negative Staphylococci (CoNS) and several other microorganisms. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are the two major omega-3 polyunsaturated fatty acids (omega-3 PUFAs) with antimicrobial properties. Materials and Methods: In this study, we tested the EPA and the DHA for its antibacterial and anti-biofilm activity in vitro against Staphylococcus epidermidis, Staphylococcus aureus, and different CoNS as reference strains and isolated from patients undergoing orthopedic treatment for implant infections. The tests were carried out with the strains in planktonic and biofilm form. Cytotoxicity assay was carried out with EPA and DHA using human gingival fibroblasts HGF-1. Results: The highest concentration of EPA and DHA promoted the complete killing of S. epidermidis 1457 and S. aureus ATCC 25923 in planktonic form. The fatty acids showed low activity against P. aeruginosa. EPA and DHA completely killed or significantly reduced the count of planktonic bacteria of the patient isolated strains. When incubated with media enriched with EPA and DHA, the biofilm formation was significantly reduced on S. epidermidis 1457 and not present on S. aureus ATCC 25923. The reduction or complete killing were also observed with the clinical isolates. The pre-formed biofilms showed reduction of the cell counting after treatment with EPA and DHA. Conclusion: In this study, the omega-3 PUFAs EPA and DHA showed antimicrobial and anti-biofilm activity in vitro against S. aureus, S. epidermidis, and P. aeruginosa, as well as against multi-drug resistant S. aureus and CoNS strains isolated from patients undergoing periprosthetic joint infections (PJI) treatment. Higher concentrations of the fatty acids showed killing activity on planktonic cells and inhibitory activity of biofilm formation. Although both substances showed antimicrobial activity, EPA showed better results in comparison with DHA. In addition, when applied on human gingival fibroblasts in vitro, EPA and DHA showed a possible protective effect on cells cultured in medium enriched with ethanol. Further studies are required to confirm the antimicrobial activity of EPA and DHA against multi-drug resistant strains and pan-drug resistant strains.