Aeromonads are Gram-negative opportunistic bacteria, initially thought to be nonpathogenic. Increasingly they are recognized as causes of gastroenteritis in both children and adults.
The typical presentation is bloody diarrhea, sometimes chronic, accompanied by nausea, vomiting, and cramping pain. The diarrhea may contain mucus as well as blood. The duration of illness varies widely, ranging from a few days to several years, indicating that Aeromonas infection can cause chronic colitis.