Which bacteria is most likely responsible for watery, yellow-green stools with abdominal pain in an elderly patient?

The choice of Shigella as the responsible bacteria for watery, yellow-green stools accompanied by abdominal pain in an elderly patient is well-founded in clinical understanding. Shigella is known for causing gastroenteritis, typically presenting with symptoms such as diarrhea (which can be watery and sometimes bloody), abdominal cramps, fever, and nausea. The stools can often appear mucoid and may have a yellowish-green tint, which aligns with the symptom description.

Moreover, elderly patients are particularly vulnerable to infections due to factors such as a weakened immune system, coexisting health conditions, and potentially diminished gastric acid production, which can make them more susceptible to pathogens like Shigella. This organism is transmitted via the fecal-oral route and can lead to significant morbidity in this age group, necessitating prompt medical attention.

In comparison, other pathogens listed, while also capable of causing gastrointestinal symptoms, may not align as closely with the described stool characteristics or the typical presentation in elderly patients. For instance, Adenovirus generally causes viral gastroenteritis, leading to less severe symptoms and is not as classically associated with the color and type of stools described. Campylobacter jejuni typically causes diarrhea that is often bloody rather than watery and can have a distinct association with