Implant-associated biofilms of Staphylococcus aureus and Enterococcus faecalis clinical isolates on expanded polytetrafluoroethylene suture in Galleria mellonella model

Implant-associated biofilm infections, particularly those caused by Staphylococcus aureus and Enterococcus faecalis, present significant challenges in clinical settings, often necessitating surgical removal. This study investigates the potential of the invertebrate model Galleria mellonella for evaluating biofilm formation of S. aureus and E. faecalis clinical isolates, the leading causes of implant-associated infections. Utilizing expanded polytetrafluoroethylene (ePTFE) sutures as a surrogate for cardiac implants, we employed two biofilm formation methodologies reflecting the two main routes of implant infections: in vivo biofilm formation within larvae mimicking pathogen spread and pre-formed biofilm transplantation. Scanning electron microscopy revealed complex biofilm structures for the biofilm formed inside of the larvae on implant, closely mimicking clinical implant biofilm. Antibiotic combination of vancomycin and rifampicin demonstrated mean 5 log₁₀ reductions in bacterial CFU count per larva and 50% improved survival, proving highly effective. The study highlights the G. mellonella model's potential for preclinical biofilm research, offering a cost-effective and ethical alternative to vertebrate models while providing valuable insights into biofilm-related infections and their treatment.