Optimization and Characterization of a Reproducible Fecal Intraperitoneal Injection Sepsis Model: Divergent Dynamics from Cecal Ligation and Puncture

Sepsis research necessitates reliable animal models to translate therapeutic interventions. This study aimed to optimize a reproducible fecal intraperitoneal injection (FIP) murine model and systematically compare its dynamics with the conventional cecal ligation and puncture (CLP) method. Our results demonstrated that fresh fecal suspensions significantly improved model reproducibility compared to dried preparations. A standardized dose of 0.7 g/kg was identified as optimal for simulating moderate-to-severe sepsis. Multi-dimensional evaluation revealed divergent disease trajectories: the FIP model was characterized by earlier bacteremia peaks and rapid acute lung and kidney injury within 24 h, whereas the CLP model exhibited more protracted organ dysfunction and sustained intestinal damage. In conclusion, the optimized FIP model, characterized by its procedural simplicity, high controllability, and superior reproducibility, serves as a robust and cost-effective platform for investigating early pathophysiological mechanisms and evaluating novel therapeutic interventions in sepsis.