Research in the Schauer laboratory takes a systems approach to understanding bacterial pathogenesis. Infectious bacteria interact with host cells by presenting pathogen-associated molecular patterns, by elaborating secreted toxins, and by delivering effector molecules via dedicated secretion systems. The outcome of infection is determined by host responses to these microbial signals. By studying naturally occurring pathogens of mice, cross-talk between the bacterium and host can be investigated at the level of the cell, tissue, organ, and organism. A particular focus is understanding how bacterial infection in the gastrointestinal tract leads to conditions such as inflammatory bowel disease, hepatitis, and cancer.