Rice water stools often contain a pure culture of which organism?

Rice water stools are characteristic of cholera, which is primarily caused by the bacterium Vibrio cholerae. This organism leads to severe watery diarrhea, which can result in dehydration and electrolyte imbalances. The term "rice water stools" describes the appearance of the diarrhea, which is pale and watery, resembling the water used to rinse rice.

Vibrio cholerae is transmitted through contaminated water and can lead to explosive outbreaks in regions with inadequate sanitation. In cases of cholera, stool samples often show a pure culture of Vibrio cholerae, making it the definitive organism associated with this clinical presentation.

In contrast, the other organisms listed have different associations and clinical presentations. For instance, Escherichia coli can cause several types of gastroenteritis, but its stools do not have the typical "rice water" appearance. Salmonella typhi is responsible for typhoid fever, which presents with a different type of diarrhea and systemic symptoms. Shigella dysenteriae typically causes dysentery, characterized by bloody diarrhea rather than the watery stools associated with cholera. Thus, the presence of a pure culture of Vibrio cholerae in rice water stools is a clear indicator of cholera infection.