The Emergency Room seems busier than usual, and the cases coming in are all too similar.  Everyone seems to be suffering from the same symptoms - abdominal pain, vomiting, and bloody diarrhea.  Once the hospital staff identify the bacteria causing the problems, the next step is tracking down the source.  This case uses a story of microbial contamination, combined with lab experiments, to teach skills in problem-solving, critical thinking, and experimental design and analysis.  It was developed for a general microbiology course primarily composed of health care students and biology majors planning to transfer to four-year schools. There are three labs associated with this case.