The GIExC simulates the complexity of stool specimens by incorporating a polymicrobial mix of inactivated bacteria, protozoa, and optional viral components relevant to gastrointestinal diagnostics. Organisms are selected to cover a range of extraction challenges, including spore-formers, anaerobes, and cyst-forming parasites. This control supports end-to-end validation of GI pathogen assays by ensuring robust lysis and nucleic acid recovery from diverse and complex input matric