Caliper- A PerkinElmer Company 1 article published in JoVE Immunology and Infection 4D Multimodality Imaging of Citrobacter rodentium Infections in Mice James William Collins1, Jeffrey A Meganck2, Chaincy Kuo2, Kevin P Francis2, Gad Frankel1 1MRC Centre for Molecular Bacteriology and Infection, Division of Cell & Molecular Biology, Imperial College London, 2Preclinical Imaging, Caliper- A PerkinElmer Company Multi-modality imaging is a valuable approach for studying bacterial colonization in small animal models. This protocol outlines infection of mice with bioluminescent Citrobacter rodentium and the longitudinal monitoring of bacterial colonization using composite 3D diffuse light imaging tomography with μCT imaging to create a 4D movie of C. rodentium infection.