Clostridium difficile is a ubiquitous, motile, rod-shaped, gram positive bacteria that is a regular resident in soil, and in low numbers is a harmless but frequent colonizer of the human gut. However, patients given broad-spectrum antibiotics to treat another bacterial infection commonly incur gastro-intestinal infections of C. difficile, which thrives when antibiotic treatments reduce normal bacteria gut fauna that would ordinarily out-compete C. difficile. In these large blooms, C. difficile releases toxins that cause flu-like symptoms, pseudomembranous colitis and in severe cases toxic megacolon, acute distension (bloating) of the colon which carries significant risk of death.

Especially common in hospitals and nursing homes, C. difficile infections have recently been on the rise and are three times as common in hospitals as they were in the last decade, with 336,000 cases reported in hospitalized patients in 2009. The CDC reported in 2007 that this bacteria causes 17,000 deaths per year; C. difficile infections are especially dangerous to the elderly. It is thought that a new, more drug-resistant and more virulent strain has evolved, exacerbating the incidence of infection. Attention to employing stricter hygiene measures in hospitals appears to help combat this stubborn bacteria, which tenaciously survive hand-washing and alcohol-based sanitation measures and require bleach to rid them from hospital surfaces. For patients who suffer from intractable infections, one solution is fecal transplants, to reinoculate the patient with the 25,000-30,000 bacteria that make up normal gut fauna, using feces from a healthy person.

The increased incidence of and threats posed by Clostridium difficile have been recently covered around the world in news reports and press releases by the New York Times, Oregon Public Broadcasting, CBC News, and the FDA.