Laboratory diagnosis of Clostridium difficile infection

Clostridium difficile infection (CDI) is a serious and sometimes life-threatening illness caused by toxin release from Clostridium difficile (CD), a gram-positive anaerobic bacterium. Infection with CD can cause clinical manifestations in a spectrum from asymptomatic carrier states to pseudomembranous colitis and toxic megacolon. Accurate diagnosis of CDI depends on early recognition of clinical symptoms of diarrhea, fever, and cramps especially after antibiotic use. Bacterial culture can be performed for epidemiological and antibiogram purposes during outbreaks of CDI. Culture, enzyme immunoassays (EIA), and molecular assays are useful for diagnosis of CDI. Toxigenic culture is useful to determine the cytopathic effect of the bacteria. Current Infectious Disease Society of America (IDSA) and American College of Gastroenterology (ACG) guidelines recommend using nucleic acid amplification tests or glutamate dehydrogenase (GDH) antigen followed by EIA testing for CD toxin A and B. Future studies for CDI diagnosis are looking toward toxin identification and the use of metabolomic analysis.