Harvard Health Letter

Novel therapy for C. difficile infections

The average human gut harbors between 500 and 1,000 bacterial species, the majority of which reside in the large intestine. Most of these inhabitants are helpful — indeed, essential — serving functions like producing vitamin K or stimulating the immune system. When this "intestinal microbiome" is disrupted by infection, illness, or treatment with antibiotics, a person's ability to digest food can be impaired and overall health affected.

In this country, recurrent infections with Clostridium difficile bacteria are one of the main causes of this kind of intestinal distress. C. difficile (pronounced see dif-uh-SEAL) infects as many as 7,000 hospitalized Americans a day, and treatment of those infections is a major cause of antibiotic-associated diarrhea. C. difficile competes for survival with other bacteria in the gut. Antibiotics are capable of killing many of its bacterial competitors, but often not C. difficile, which allows C. difficile to run wild.

Mild C. difficile cases are typically treated with the antibiotic metronidazole (Flagyl), and more serious cases with vancomycin (Vancocin). Both drugs are capable of killing the active form of the bacterium, but the spore form may survive. As a result, in about a fifth of cases, the spores spring to life once treatment with the antibiotic has stopped. After C. difficile recurs, over half of all patients may develop chronic, and potentially fatal, infections.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »