A patient develops bloody diarrhea days after eating raw spinach. Which agent fits best?

1. A serotype is a strain carrying a particular set of surface antigens, and one species may have many. 2. Most E. coli are not particularly dangerous to humans. 3. Serotype O157:H7 is the exception: it can cause bloody diarrhea and is potentially fatal. 4. The 2006 raw spinach outbreak in the United States was produced by exactly this serotype. 5. Typhoid presents with intestinal hemorrhage and high fever after feces-borne spread, not after a salad. 6. Botulism is a toxin illness from anaerobic packaging, and plague arrives by flea bite, so neither matches produce. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 22 "Prokaryotes: Bacteria and Archaea", section 22.4 Bacterial Diseases in Humans_