A new defence against Clostridium difficile, a deadly superbug that kills hundreds and sickens thousands every year, is coming to Canada.

Optimer Pharmaceuticals Canada Inc. will announce Thursday it has received Health Canada approval to market fidaxomicin, sold under the brand name Dificid, to treat C. difficile infections in adults.

Infections occur when antibiotics kill the healthy bacteria found in the gut, allowing the antibiotic-resistant C. difficile bacteria to grow and produce toxins that can lead to mild or severe diarrhea. Although there are no national statistics collected, estimates indicate hundreds of people die from C. difficile infections in Canada every year.

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Dificid is the first of a new class of antibiotics known as macrocycles to gain approval in Canada. In clinical trials, Dificid worked as well as the front-line treatment vancomycin in treating infections. But patients taking Dificid had a lower relapse rate than the existing treatment. That's significant, considering about 20 per cent of patients will have a recurrence of C. difficile after being treated. Dificid targets C. difficile bacteria while preserving healthy gut bacteria, which is believed to help reduce the chance of recurrence.

"We are proud to have the opportunity to bring this first-in-class antibiotic to help Canadian patients in need," Paulash Mohsen, president and country manager for Optimer Canada, said in a media release.

The drug company declined to specify the price range for the drug in Canada, but made headlines last year when it decided to charge $2,800 (U.S.) for a 10-day treatment course, about double the cost of vancomycin.

Beyond the issue of cost, one of Canada's most prominent infectious disease experts warns that Dificid isn't the answer to our prayers.

"It's always good news to have another drug to treat something. It certainly isn't a panacea, however," said Michael Gardam, director of infection prevention and control at the University Health Network in Toronto.

Dr. Gardam points out that while patients taking Dificid had lower rates of relapse, many still suffered recurrent cases of C. difficile. There is also some evidence emerging that bacteria are becoming resistant to the new drug.

"The answer in life is almost never a new antibiotic because they have very short lifespans," Dr. Gardam said.

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The discussion of drugs also ignores the root cause of C. difficile infections, he said. Many people who contract infections were prescribed antibiotics unnecessarily and others are exposed to the bacteria in contaminated environments. More needs to be done to prevent infections in the first place, Dr. Gardam said.