What makes C-Diff superbug deadly?

Mar 01, 2009

A major breakthrough about the potentially deadly superbug Clostridium difficile (C-diff) could lead to new ways to combat the bacterium, according to a study to be published March 1 in the journal Nature.

The study reveals that for decades researchers have been focusing on the wrong toxin that is released by the bacteria in the colon. The toxin can cause severe diarrhea and life-threatening colitis that could lead to the surgical removal of the colon.

"For 20 years, we have been focusing on Toxin A. But it turns out the real culprit is Toxin B," said study co-author Dr. Dale Gerding. "This is a major finding in how C-diff causes disease in humans. It completely flips our whole concept of what the important toxin is with this disease."

Gerding is a professor of medicine, division of infectious diseases, Loyola University Chicago Stritch School of Medicine, Maywood, Ill., and associate chief of staff for Research, Hines VA Hospital.

C-diff is a spore-forming bacterium that was discovered in 1978 to be the cause of antibiotic-associated diarrhea and colitis. It is rapidly spreading through health-care facilities around the globe. When the normal bacteria that live in the colon are disturbed, usually as a result of antibiotic treatment, and a patient ingests C-diff spores, the bacteria can multiply and release the two toxins.

C-diff sickens about 500,000 Americans a year, contributing to 15,000 to 20,000 deaths, The epidemic strain has been found in 38 states, including Illinois. It now rivals the superbug known as MRSA as one of the top emerging disease threats to humans. Since its discovery, C-diff has grown increasingly resistant to antibiotics. Though it is appearing more often in younger people, those 65 years and older face a greater risk of developing infection from C-diff and have more severe outcomes and higher death rates.

Symptoms of C-diff include profuse diarrhea and abdominal pain and distention of the abdomen. An infection is also frequently accompanied by fever, nausea and dehydration. In some rare cases blood may be present in the stool. The infection is spread by spores that contaminate the hospital environment and hands of healthcare workers who can transmit the spores to patients. The resistance of the spores to hospital cleaning agents and to alcohol hand disinfectants makes it extremely difficult to eradicate.

Gerding noted that a human clinical trial using a drug that bound Toxin A more than it bound Toxin B failed to treat C-diff effectively.

"There's probably a good reason why the trial failed," Gerding said. "We now know that Toxin B should have been the primary target."

The study has major implications for the future development of treatments and preventative measures for C-diff, said Gerding and co-author Dr. Stuart Johnson, associate professor of medicine, division of infectious diseases, Loyola University Chicago Stritch School of Medicine.

"The more you understand the way an organism causes disease, the better you can target treatment or preventative measures," said Johnson, who has treated dozens of C-diff patients.

The breakthrough in the study came after co-authors in Australia engineered mutant strains of the bacteria that were tested by Gerding and other Loyola researchers.

"It turns out that in the strain in which Toxin A was knocked out, the organism was fully virulent. It caused disease," Johnson said. "When they knocked the Toxin B out in another set of experiments, the organism didn't cause disease. This is probably the best evidence to date about the relative importance of these two toxins."

Source: Loyola University Health System

Explore further: Restrictions lifted at British bird flu farm

add to favorites email to friend print save as pdf

Related Stories

Biochemical pathways may be key to scab resistance

Feb 26, 2014

Pale, shriveled heads of grain spell trouble for wheat and barley farmers—they're the telltale signs of Fusarium head blight. The fungal disease, commonly known as scab, not only dramatically shrinks yields ...

Yeast models of cell death and survival mechanisms

Oct 19, 2012

European scientists investigated differences in the genomes of various distantly-related yeast and their effects on cell survival. Results may provide insight into cell death induced by free radicals.

A sweet defense against lethal bacteria

May 31, 2011

(PhysOrg.com) -- There is now a promising vaccine candidate for combating the pathogen which causes one of the most common and dangerous hospital infections. An international team of scientists from the Max ...

Recommended for you

Restrictions lifted at British bird flu farm

18 hours ago

Britain on Sunday lifted all restrictions at a duck farm in northern England after last month's outbreak of H5N8 bird flu, the same strain seen in recent cases across Europe.

Recorded Ebola deaths top 7,000

Dec 20, 2014

The worst Ebola outbreak on record has now killed more than 7,000 people, with many of the latest deaths reported in Sierra Leone, the World Health Organization said as United Nations Secretary-General Ban ...

Liberia holds Senate vote amid Ebola fears (Update)

Dec 20, 2014

Health workers manned polling stations across Liberia on Saturday as voters cast their ballots in a twice-delayed Senate election that has been criticized for its potential to spread the deadly Ebola disease.

Evidence-based recs issued for systemic care in psoriasis

Dec 19, 2014

(HealthDay)—For appropriately selected patients with psoriasis, combining biologics with other systemic treatments, including phototherapy, oral medications, or other biologic, may result in greater efficacy ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.