Clostridium difficile is a species of rod shaped bacteria that can encapsulate itself in spores. The spores of this bacteria are resistant to many cleaning methods used and can live outside of conditions normal for bacterial growth for extended periods of time. When ingested in the human body the spores can lay dormant in the large intestine. After a person has taken a strong, broad spectrum antibiotic to clear out some infection this wipes out the standard bacterial population in the large intestine. This allows the spores to open and the bacteria to multiply and take over the large intestine since there is no competition from other bacteria. Clostridium difficile can cause painful intestinal bloating and diarrhea if left untreated.