{Reference Type}: Systematic Review {Title}: Nonmammalian models to study Clostridioides difficile infection; a systematic review. {Author}: Hu C;Garey KW; {Journal}: Anaerobe {Volume}: 79 {Issue}: 0 {Year}: Feb 2023 {Factor}: 2.837 {DOI}: 10.1016/j.anaerobe.2023.102694 {Abstract}: Clostridioide difficile is the leading cause of diarrhea disease worldwide and is a CDC-designated urgent threat level pathogen. Mammalian models are commonly utilized as gold standard to study the pathogenesis of C. difficile infection (CDI); however, alternatives are needed due to cost, higher throughput ability, and mammalian animal ethics. Nonmammalian models such as great wax worm, nematode, fruit fly, and zebrafish have been used as CDI models. This review provides a comprehensive summary of nonmammalian models used to study CDI. Multiple studies were identified using these models to study C. difficile infection, pathogenicity, colonization, host immunity, and therapy. Translational outcomes and strength and weakness of each nonmammalian model are discussed.