Clostridium Difficile: New Intestinal Superbug

Members of the bacterial genus Clostridium have been around for ages, causing a wide range of deadly diseases, including tetanus, botulism and gangrene. Several unusual characteristics make them such tough little 'bugs'.

Clostridium Can Form Endospores

Although Clostridium are a Gram-positive, anaerobic type of bacteria killed by exposure to oxygen, they can also form resistant structures called endospores (somewhat like a 'bacterial seed') when stressed. Endospores can remain dormant for decades, germinating into living bacteria under optimal conditions for their growth and success.

Besides being able to go dormant under unfavorable conditions, members of this genus also produce a variety of very potent toxins which can cause severe illness. Clostridium difficile (pronounced claw-STRID-ee-um DIFF-uh-seal) is a specific member of this toxic group that has recently been getting a lot of attention.

Some People Carry C. diff Without Getting Sick

Clostridium difficile is actually a species of bacteria that, in a small portion of the population, normally inhabits the human gut without causing disease. In a healthy human carrier, the C. diff population remains small and the bacteria do not exist in large enough numbers to cause illness.

CDF Infection

Severe C. diff infection of the colon most often occurs after a patient has taken a course of broad-spectrum antibiotics, killing much of the normal gut flora. Broad-spectrum antibiotics indiscriminately kill both good and bad bacteria. Any CDF not killed by the antibiotics can multiply without competition from other microbes, and become overgrown.

C. diff overgrowth is harmful because the toxins released by the bacteria can cause:

1. Bloating and constipation
2. Severe diarrhea
3. Intense abdominal pain caused by ulcerated intestines

These symptoms, in combination with foul stool odor and recent treatment with broad-spectrum antibiotics, are suggestive of Clostridium difficile infection (CDI).

Why Doesn't C. diff Make Everyone Sick?

Clostridium difficile infection does not affect everyone the same way. Some people show no symptoms whereas others develop severe, life threatening pseudomembranous colitis.

Pathenogenicity is affected by the specific virulence of the C. diff strain causing the infection. ('Virulence' essentially means how good the bacteria is at being harmful). Part of the variability in symptoms is also due to how well a person's immune system is functioning. Immunocompromised patients, and those whose treatment is delayed (usually due to misdiagnosis), have a higher risk of death from CDI. Getting a correct diagnosis can be tricky, since initial CDI symptoms can be flu-like.

How Is C. diff Transmitted?

CDF is transmitted from person to person via the fecal oral route. People can become infected when they touch things that are contaminated with feces and then touch their mouth or other mucous membranes.

Since C. diff produces endospores, it is very difficult to eliminate in the surrounding environment. Bleach is one chemical agent that can successfully destroy C. diff cells and endospores found on surfaces or in water.

Treatment of CDI

Early intervention and aggressive treatment are the key factors in a successful recovery from CDI. With so many strains of C. diff now resistant to antibiotics, severe infection can only be treated through use of specific anticlostridial antibiotics, such as metronidazole and vancomycin.

Sources

Bauman, R. (2004) Microbiology. Pearson Benjamin Cummings.

Talero, K. P (2008) Foundations in Microbiology Basic Principles. McGraw Hill Companies.

For more information on microbes and infectious disease, see the SPO Virtual Microbiology Classroom and the CDC Public Health Image Library (PHIL).

Note: This article, originally published in Suite101 online magazine, is not meant to be used in the treatment of illness or disease. If you are sick, please see a physician, not a computer.