The large intestine (also known as the colon) is responsible for the absorption of water and compaction of feces. Although bacteria typically are able to live in the colon without causing any active infection, the colon is susceptible to infection. Sometimes this is caused by dangerous bacteria gaining access to the colon via contaminated food, and other times it is caused by overgrowth of the bacteria (which can be caused by antibiotic use).
Diarrhea
As InteliHealth explains, patients with infectious colitis commonly experience diarrhea as a result of inflammation and tissue damage to the lining of the intestines. The intestines are lined with small protrusions called villi, which increase the surface area of the tissue, allowing for food to be absorbed. Infections of the intestines can lead to the villi becoming destroyed, impairing nutrient absorption. The lack of nutrient absorption means that the feces become bulkier and can become watery, as the large intestine is unable to absorb water properly. If the diarrhea is severe and goes untreated, it can also lead to dehydration and kidney damage (as a result of fluid loss).
Nausea, Pain and Fever
MD Consult, citing the Sabiston Textbook of Surgery, explains that many types of infectious colitis can also lead to nausea and vomiting. These symptoms are caused by the body's reaction to the infection. Patients may also experience abdominal pain and a fever as a result of the inflammatory response that is triggered by the infection.
Intestinal Bleeding
Many bacteria that infect the colon can cause tissue damage. This can lead to the lining of the intestines becoming worn down, leading to the appearance of blood in the stool. Because the source of the bleeding is located in the colon, the blood will typically be bright red in appearance and is often mixed with pus in the diarrhea.
Intestinal Perforation
The Mayo Clinic notes that certain kinds of infectious colitis, including that caused by the bacterium C. difficile, can lead to perforation of the intestinal wall. Intestinal perforation is marked by a sudden onset of severe abdominal pain, as well as nausea, vomiting and a very high fever. Infectious colitis can cause intestinal perforation as a result of the bacteria breaking down the intestinal lining. It can also occur if inflammation and scar tissue causes the colon to be blocked off, leading to a condition known as toxic megalocolon. When this happens, fecal matter and gas accumulates and increases the pressure in the colon until it ruptures.
