[Comparison of different biomaterials for vaginal surgery using an in vivo model of meshes infection in rats].

Objectives: The purpose of this study was to develop an animal model of prosthetic infection and compare in vivo bacterial infectiosity of different biomaterials used in vaginal surgery.
Materials and Methods: We implanted 36 prostheses of poly(lactic acid) with 94% L forms (PLA94), in a model of incisional abdominal hernia in Wistar rats. Bacterial inoculation was done just after implantation with three strains of Escherichia coli of variable virulence, two different concentrations and two different times of inoculation (during surgery or 48 hours after). All meshes were explanted and animals sacrificed on day 30 after intervention. Bacteriology and histology were then performed. In the same way, three materials used in vaginal surgery (knitted light-weight polypropylene [PP], thermoformed PP [Uratape] and polyurethane coated poly[ethylene terephtalate] [PTFE]) were tested and compared to the PLA94 using the same protocol.
Results: All inoculated prostheses were still infected at day 30 after implantation with the same E. coli strain. There was a significant difference in bacterial infectiosity linked to virulence of the inoculated strain (p=.005) and the amount injected (P<0.001). Infectiosity was significantly lower for PLA94 when compared to the three other prostheses (P=0.008). The most important infectiosity was seen with PTFE and thermoformed PP. For histologists, PLA94 also gave the weakest inflammatory reaction.
Discussion and Conclusion: An original animal model of prosthetic infection allowed us to compare in vivo bacterial infectiosity of different biomaterials used in vaginal surgery and to demonstrate that the PLA94 mesh induces a milder risk of infection than polypropylene.