Pseudomembranous colitis is a type of inflammatory disorder of the large intestine, or colon. It is linked to the use of antibiotics. If you take an antibiotic to treat an infection, it can lead to an increase in the bacteria called Clostridioides difficile, or C. diff, that live in your colon. This bacteria can grow too much, causing the disease. Pseudomembranous colitis occurs more often in people who are in hospitals and nursing homes. Older people and people who have other illnesses or conditions that need to take antibiotics for a long time are at a higher risk. The bacteria C. diff is found in the infected person's stool or feces. Other people can be infected if they touch a surface contaminated with feces, such as a hand or toilet seat.