Squashing a superbug
Mon, December 4, 2006
New toxin binder shows promise in controlling aggressive bacterium plaguing hospitals
By LAURA CZEKAJ
As threats of a new and more aggressive strain of C. difficile loom large in Quebec, medical experts are in the final stages of testing a new drug that is being described as a potential lifesaver.
Eleven people have died from Clostridium difficile since July at Honore-Mercier Hospital in St-Hyacinthe, southeast of Montreal. The Quebec government has ordered a coroner's inquest into the deaths.
Experts fear this might be the start of yet another deadly outbreak to hit the province.
Roughly 2,000 people were killed by a deadly strain of C. difficile in Quebec between 2003 and 2004. In the U.S., infectious-disease experts estimate that the superbug kills more than 5,000 people annually.
It's a bacterium that causes diarrhea and other serious intestinal conditions and is one of the most common infections found in hospitals and long-term care facilities.
C. difficile outbreaks are increasing in severity due to the aging population, the overuse of antibiotics and new, more virulent strains.
Ironically, the problem that is caused by antibiotics is also treated by antibiotics.
"Antibiotics were not really the major problem, but they were definitely the triggering factor," said the Universite de Montreal's Dr. Karl Weiss, who works out of the Maisonneuve-Rosemont Hospital. "So we had to be sure that when we prescribed antibiotics we prescribed them wisely and not for a long period of time."
Weiss is one of the investigators in North American clinical trials for a new drug called Tolevamer, a treatment developed by drug company Genzyme.
Tolevamer is not an antibiotic but a toxin binder which prevents the toxin released by C. difficile from attaching to cells.
In Phase 2 trials, there was a trend for a high dose of the drug to decrease the likelihood of recurrence. Weiss said that while the drug's promising performance doesn't assure success, it does bode well going into the next trial stage.
"The good thing is that at least we seem to have a new option for treating C. difficile, something we didn't have for the last 20 years," he said. "It's not going to be a miracle drug, but it's definitely a new addition in our fight against C. difficile."
C. difficile has been what Weiss calls an orphan disease. Since 1978 when the first cases of the infection came to light, there haven't been any new drugs on the market.
The Public Health Agency of Canada has conducted a national study involving 41 hospitals in nine provinces which compares the findings of a similar study done in 1997 with findings from a period straddling 2004-2005.
Overall, the study found that hospitals across the country had on average six cases of patients who contracted C. difficile in hospital per 1,000 admissions, which differs little from 1997 where it was 5.9 per cent. The difference was that more patients are dying than in 1997.
Of the people in 2004-2005 who contracted the infection, about 5.7 per cent of them died from causes directly or indirectly related to C. difficile. The death rate in 1997 was 1.5 per cent.
The study also examined C. difficile strain characteristics.
"Having one of these new strains, the more virulent strains, was strongly predictive of death," said Dr. Virginia Roth, director of the infection control department of the Ottawa Hospital, one of the hospitals that participated in the study.
In acute care hospitals across Canada, the transmission of C. difficile from patient to patient is a hazard, she said.
If successful in clinical trials, it could be more than a year before Tolevamer is on the market.
"We have to look at it in a positive way because we didn't have anything for the last 20 to 30 years," said Weiss. "C. difficile was not really on the radar screen for a while."
lfpress.ca |
