Clostridium difficile

Clostridium difficile

Organism

Clostridium difficile is a moderately-sized gram-positive, endospore-producing bacillus.
Motile with a peritrichous (def) arrangement of flagella.
An obligate anaerobe (def).

Habitat

Colonizes the intestinal tract in a small proportion of healthy humans.

Source

Transmitted person to person by the fecal-oral route.

Epidemiology

Colonizes the intestinal tract in less than 5% of healthy humans.
Endospores are frequently found around the beds and bathrooms of infected individuals.
Exposure to antibiotics is associated with overgrowth of C difficile in the intestine and development of antibiotic-associated colitis.
Antibiotic-associated colitis is especially common in older adults. It is thought that C. difficile survives the exposure to the antibiotic by sporulation. After the antibiotic is gone, the endospores germinate and C. difficile overgrows the intestinal tract and secretes toxin A and toxin B that have cytotoxic effects on the cells.

Clinical Disease

Can range from self-limiting diarrhea to potentially fatal pseudomembranous colitis (def).

Pathogenicity

Toxin A (enterotoxin) attracts phagocytes to the area, triggers cytokine (def) production and hypersecretion of fluids; tissue damage from phagocytes and inflammation leads to hemorrhagic necrosis (def).
Toxin B depolymerizes actin causing damage to the host cell's cytoskeleton.
Cell wall adhesins (def) allow the bacteria to attach to cells of the colon (def).
Endospores enable the bacterium to survive in hospital environments.

Treatment

Treatment is typically with vancomycin or metronidazole* (see antibiotic table).

*Drugs may change with time.

For a more detailed article on Clostridium difficile, see Clostridium difficile Colitis, by Craig A Gronczewski, MD, Staff Physician, Department of Emergency Medicine, Medical College of Pennsylvania; and Jonathan P Katz, MD, Instructor, Department of Medicine, University of Pennsylvania School of Medicine.