Galleria mellonella model for studying Gram-positive bacterial implant biofilms

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 development within larvae mimicking hematogenous spread and pre-formed biofilm transplantation mimicking contamination during surgery. Scanning electron microscopy revealed complex biofilm structures for the biofilm formed inside of the larvae on implant, closely mimicking clinical conditions. Antibiotic treatments with vancomycin and rifampicin demonstrated significant reductions in bacterial biofilms, proving highly effective. The study highlights the G. mellonella models 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.