<i>In vivo</i> Analysis of the Resistance of the Meshes to <i>Escherichia coli</i> Infection.

Abstract

<b>Background:</b> The mesh infection is mostly related to the gram-negative bacteria, such as Escherichia coli (<i>E. coli</i>) for emergency surgery of incarcerated hernia. However, few study investigated the effects of <i>E. coli</i> concentration, mesh materials and antibiotic prophylaxis on mesh infection after hernioplasty. The aim of this study was to evaluate the bacterial resistance to <i>E. coli</i> for three different materials of mesh, and to measure the minimum <i>E. coli</i> concentration for mesh infection with and without antibiotic prophylaxis in a rat model. <b>Methods:</b> Three types of mesh (polytetrafluoroethylene, polypropylene, and biologic meshes) were used in the repair of an acute ventral hernia rat model in the setting of different concentrations of <i>E. coli</i> loads and antibiotics. At the 8th day after surgery, mesh samples were sent for microbiologic and histologic analyses. <b>Results:</b> The positive rates of bacterial culture increased with <i>E. coli</i> concentration. The biologic mesh showed better bacterial resistance compared to polytetrafluoroethylene mesh and polypropylene mesh when the concentration of <i>E. coli</i> ranges from 10⁶ CFU/ml to 10⁸ CFU/ml (<i>P</i> = 0.002 and <i>P</i> = 0.029, respectively). Prophylactical ceftriaxone treatment could not decrease the colonization rate of <i>E. coli</i> at 10⁶ CFU/ml or 10⁸ CFU/ml in each group (<i>P</i> > 0.05). The scores of neovascularization in polypropylene mesh and biologic mesh were similar, which was higher than that of polytetrafluoroethylene mesh (<i>P</i> < 0.05). Compared with other meshes, biologic mesh showed better tolerance to 10⁶ CFU/ml <i>E. coli</i> with respect to inflammation, depth of inflammation, neovascularization, cellular repopulation and foreign body giant cells. <b>Conclusion:</b> The biologic mesh had better <i>E. coli</i> resistance compared to polytetrafluoroethylene mesh and polypropylene mesh when the <i>E. coli</i> concentration is higher than 10⁶ CFU/ml in rats. Antibiotic prophylaxis was useful when the contamination was not particularly severe.