C. difficile is part of the normal flora of the gastrointestinal tract. This anaerobic spore-forming bacterium opportunistically dominates when other competing gastrointestinal flora are impacted by the use of antibiotics.

C. difficile has become one of the most serious nosocomial pathogens, impacting hospitals (ICU, post-operative and cancer wards), nursing homes, and other medical institutions. C. difficile spores aide the spread of the organism within hospitals and confer resistance to all cleaning agents and detergents except those containing bleach. C. difficile causes diarrhea, from the mild to the most severe form of antibiotic associated diarrhoea and pseudomembranous colitis (PC). PC is a severe inflammation of the colon which can be life threatening, especially among the elderly. PC due to C. difficile infection is associated with toxigenic strains.

The clinical symptoms of PC are primarily associated with toxin A, the tissue-damaging enterotoxin. C. difficile also produces toxin B, a cytotoxin. C. difficile strains produce either both toxins, toxin B or neither. Detection of these antigens in stool samples is a reliable indicator of toxigenic strains (only these strains produce the toxin antigens). C. difficile glutamate dehydrogenase (GDH) is a sensitive screening marker for the detection of the organism in faecal specimens. This marker reliably detects both toxigenic and non-toxigenic strains.