Think of "E. coli," and you probably picture outbreaks of foodborne illnesses that can cause severe stomach cramps, vomiting and more. After all, certain strains of the bacterium are among the most common and potentially lethal causes of food poisoning.
But there are other strains of E. coli. Some are harmless gut bacteria, but others—specifically, Extraintestinal Pathogenic Escherichia coli (ExPEC)—are dangerous, and even fatal, particularly if you're an older adult. And due to rising antimicrobial resistance, the antibiotics used to fight dangerous infections caused by ExPEC, like bacteremia, which occurs when bacteria enters the blood, and sepsis, the body's extreme and dangerous reaction to infection, are becoming less effective.