Development of a Novel Murine Model for Treatment of Infected Mesh Scenarios

Arnab Majumder, Clayton Petro, MD, Lijia Liu, MD, Mojtaba Fayezizadeh, MD, Kasim Aydogdu, MD, Yuri W Novitsky, MD, FACS. Department of Surgery, University Hospitals Case Medical Center, Cleveland, OH

Introduction: Despite advances in hernia surgery, mesh infection remains a significant challenge. Indications regarding repair after removal of a previously infected prosthesis remain unclear. Although patients in these circumstances may receive biologic implants or staged primary repair with deferred definitive reconstruction, neither may be ideal management. While various animal models have simulated contamination by direct inoculation of implants with bacteria, there remains a paucity in literature which truly simulates a field following mesh infection and removal. We aimed to develop a murine model to mimic this complex scenario to allow for further testing of various implants and coatings.

Materials and Methods: Thirty-six female CL57BL/6J mice underwent open implantation of a 0.7×0.7cm piece of polyester mesh in the dorsal-subcutaneous position. Wounds were closed and subsequently inoculated with 0.1mL of 104 GFP labeled MSSA. After two weeks the infected mesh was removed and the cavity was copiously irrigated with saline. Mice were split into four groups:  with three groups receiving new polyester, polypropylene, and biologic mesh and remaining as non-mesh controls. Mice were survived for another two weeks and underwent necropsy. Gross infection was evaluated at two and four weeks. Tissue homogenization and direct plating to recover GFP MSSA was completed at four weeks.

Results: At two weeks all mice were noted to have gross mesh infection. One animal died due to overwhelming infection and wound breakdown. At four weeks, 5/6 (83%) control mice who did not have a second mesh implantation had full clearance of their wounds. In contrast 9/9 (100%) mice with re-implantation of Parietex were noted to have pus and recovery of GFP MSSA on plating. This was also observed in 90% of mice with polypropylene mesh and 100% of those with biologic mesh.

Conclusion: Our novel murine model demonstrates that mesh re-implantation after infected mesh removal results in infection of the newly placed prosthesis, regardless of the material characteristic or type. This model lays foundation for development and investigation of implants for treatment strategies following infected mesh removal.