Clostridium defficile are bacteria which are usually present in our GI tract without any harm. These bacteria can cause infection when antibiotics are used for other illness. This antibiotics can kill beneficial bacteria which inhibit the growth of C. Difficile. In the absence of these beneficial bacteria, C. Difficile can grow and cause diarrhea. Symptoms of the C. Difficile infection can be seen during or immediately after antibiotic used. There are also chances that a person who has these bacteria may not develop any symptom for weeks or even months. This infection is treated by stopping antibiotic use and start using metronidazole.