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Stretchers
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Health & Safety
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Jill Mahoney
From Thursday's Globe and Mail
Published on Wednesday, Aug. 11, 2010 7:18AM EDT
Last updated on Thursday, Aug. 12, 2010 10:08AM EDT
At least two Canadians have become infected with a dangerous new superbug from India that is spreading around the world, partly due to medical tourism.
The superbug, which is resistant to almost all antibiotics, has Canadian public-health experts bracing for outbreaks.
“There will be others. It’s just a matter of time,” said Dylan Pillai, a medical microbiologist at the Ontario Agency for Health Protection and Promotion. “It’s just the nature of the beast.”
Researchers reported dozens of cases of British, Indian and Pakistani patients who contracted infections caused by bacteria harbouring an enzyme called New Delhi metallo-beta-lactamase, or NDM-1, in the journal The Lancet Infectious Diseases on Wednesday.
Of 29 Britons, more than half had recently travelled to India or Pakistan and 14 had been admitted to hospitals in the subcontinent, where the drug-resistant enzyme originated, including for kidney transplants and cosmetic surgery.
Two cases have been confirmed among Canadians who spent time in India. In addition, the drug-resistant infection has been found in patients from the United States, Sweden, the Netherlands and Australia.
The Lancet researchers called the superbug’s spread a “clear and frightening” potential “major global health problem,” noting that pharmaceutical companies are not producing new antibiotics for NDM-1 sufferers.
“At a global level, this is a real concern,” lead author Timothy Walsh, a professor of medical microbiology and antimicrobial resistance at Cardiff University in Wales, told Reuters.
“Because of medical tourism and international travel in general, resistance to these types of bacteria has the potential to spread around the world very, very quickly. And there is nothing in the [drug development] pipeline to tackle it.”
With only a couple of effective antibiotics, NDM-1 is one of the most difficult superbugs to treat. There are many more medications available for other drug-resistant infections, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE).
“It’s quite concerning because there are very limited treatment options,” Dr. Pillai said. “We’re really in a tight spot here.”
In a commentary accompanying The Lancet study, Johann Pitout, a University of Calgary professor of pathology and laboratory medicine, urged screening patients who undergo medical procedures in India before they receive treatment in their home countries.
“The consequences will be serious if family doctors have to treat infections caused by these multiresistant bacteria on a daily basis,” he wrote.
In an interview, Dr. Pitout said that his lab analyzed a sample earlier this year from an Albertan who contracted NDM-1 after being hospitalized in India. The patient has recovered.
At the time, Dr. Pitout, a medical microbiologist, was unaware of the new superbug. He said he “put two and two together” after reading medical reports out of Britain, where NDM-1 was first detected in 2008. He plans to publish a paper on the case.
As well, a Vancouver woman contracted NDM-1 in India, where she was hospitalized and treated without success, said Howard Njoo, director-general of the Public Health Agency of Canada’s Centre for Communicable Diseases and Infection Control. In February, the woman came to Vancouver, where doctors found an effective combination of antibiotics, he said.
“This case was, in a sense, not unusual because of the association and travel to India. It still underscores the fact that we haven’t had a case of this bug actually circulating in Canada,” he said.
Dr. Njoo said he was not aware of the details of the Alberta case.
NDM-1 is an enzyme that is produced by bacteria that renders most antibiotics inactive. It is commonly harboured in E. coli and Klebsiella pneumoniae. People infected with NDM-1-producing bacteria often contract urinary-tract infections, pneumonia or blood infections.
“If you get it in the hospital, this could be certainly a tipping point, and if the doctors don’t have good antibiotics to resort to, it could be very, very dangerous,” Dr. Pillai said.
The spread of NDM-1 within health-care facilities can be curbed through strict infection-control measures, including patient isolation and hand washing.
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NDM-1, which stands for New Delhi metallo-beta-lactamase-1 is a gene (DNA code) carried by some bacteria. If a bacteria strain carries the NDM-1 gene it is resistant to nearly all antibiotics, including carbapenem antibiotics - also known as antibiotics of last resort.
Carbepenems are the most powerful antibiotics, used as a last resort for many bacterial infections, such as E. coli and Klebsiella. The NDM-1 gene makes the bacterium produce an enzyme which neutralizes the activity of carbepenem antibiotics.
A bacterium carrying the NDM-1 gene is the most powerful superbug around.
Put simply:
NDM-1(New Delhi metallo-ß-lactamase-1) is the gene (the DNA code) found in some types of bacteria
This gene makes the bacteria produce an enzyme called a carbapenemase - making carbepenem antibiotics ineffective (as well as virtually all other antibiotics).
Carbepenem antibiotics are extremely powerful and used to fight highly resistant bacteria (when other antibiotics have not worked).
There are no current antibiotics to combat NDM-1
There is no research in the pipeline on drugs to combat NDM-1
A bacterium with the NDM-1 DNA code has the potential to be resistant to all our current antibiotics, as well as new antibiotics which may come into the market in the near future.
The DNA code can easily jump from one bacteria strain to another through horizontal gene transfer. IF NDM-1 jumps to an already antibiotic-resistant bacterium, there is a risk of seriously dangerous infections which would spread rapidly from human-to-human. These infections might be untreatable.
UK doctors say they had only ever seen a few cases which are resistant to carbapenems - and these had not been able to transfer resistance to other bacteria. The fact that NDM-1 can easily transfer to different bacteria strains is very worrying, they say.
Currently (12 August 2010) we know that some strains of bacteria, such as E. coli and Klebsiella pneumoniae carry the NDM-1 gene.
The origin of NDM-1
The gene was discovered by Young and team and was named after New Delhi, the Indian capital. The gene is widespread in India and Pakistan, especially in hospitals.
Europeans who have undergone hospitalization in the Indian subcontinent have brought NDM-1 back to Europe. A significant number of Europeans who brought the gene back to Europe had undergone cosmetic surgery in India/Pakistan because it is cheaper there.
How untreatable is this superbug?
So far, doctors in the UK have managed to fight these infections with a combination of several different medications. However, scientists have detected some bacterial strains that are resistant to ALL antibiotics.
The only way to currently combat the spread of NDM-1 is through surveillance, prompt identification and isolation of infected patients, disinfecting hospital equipment, and thorough hand-hygiene procedures in hospitals. This is going to be a challenge and will require international cooperation.
NDM-1 is widespread in India and Pakistan, and it has reached Europe, the USA, Canada and Australia.
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