TORONTO - Canadian researchers have shown for the first time that a treatment to rid hospital patients who are carrying but not yet infected with a potent superbug can work, potentially offering hospitals a way to both reduce the risk of illness for individual patients and lower levels of dangerous bacteria in their facilities.
A seven-day course of treatment with the new combination therapy was effective over the long term (three months) in eradicating methicillin-resistant Staphylococcus aureus - better known as MRSA - from between 60 and 70 per cent of treated patients, said the study, reported Monday in the journal Clinical Infectious Diseases.
Even at eight months 54 per cent of treated patients remained free of the bacterium, which is a major cause of hospital-acquired infections and is becoming a significant source of serious illness among non-hospitalized people as well.
Lead author Dr. Andrew Simor said this is the first study to show therapy to "decolonize" MRSA carriers can be effective over an extended period of time.
"Lots of treatment has been shown to work for a shorter period of time. But what's the point? If you clear it for a month or two but then you're positive again, you haven't gained anything," said Simor, head of microbiology at Toronto's Sunnybrook Health Sciences Centre.
The treatment is a combination of antibiotic ointment applied to skin sites where the bacteria is normally found, baths with antiseptic soap and oral antibiotics.
MRSA is one of a number of types of bacteria that are said to "colonize" people.
The bacteria can lurk in the nostrils, groin or around the anus of people who've been exposed to it without making them sick. But the bacteria can go on to trigger illness, especially when carriers go into hospital for medical care.
Between 20 and 30 per cent of carriers go on to develop an MRSA-induced illness, ranging from skin or wound infections to abscesses to pneumonia.
And MRSA carriers aren't simply a risk to themselves. They can infect other patients - which is why hospitals isolate people known to be MRSA carriers. Placing patients in isolation eats up scarce resources, says Dr. John Embil, head of infection control for the Winnipeg Regional Health Authority and director of the infection control unit of the Canadian Healthcare Association.
"The reality is in every single facility it is a colossal problem because we're decreasing the readily available number of rooms if we have to isolate people," Embil said from Winnipeg.
It's been estimated that an MRSA infection picked up in hospital adds between four and 21 days to the length of a hospital stay and costs, on average, $15,000 to treat per patient.
Simor said the most recent estimate of MRSA's cost to the Canadian health-care system is at least $250 million a year.
The treatment he and his co-authors - from several Toronto and Vancouver hospitals and from McMaster University - devised costs about $20 to $30 per treatment course.
Previous efforts to clear colonized hospital patients of MRSA have been mixed. And when they have worked the effect has been short lived.
For this study, patients found to be colonized with MRSA were randomized to receive either no decolonization treatment or were given the combination treatment.
Embil found the results impressive, but said one study doesn't generally lead to a complete switch in treatment protocols.
"You always have to be careful. You can't jump and change your entire practice based on one report. However it's certainly a very important and valuable report that may help us rethink what we do and how we do it," he said, suggested his team will likely try to decolonize carefully selected patients using this "more aggressive approach."
A commentary in the journal by Dr. Suzanne Bradley of the University of Michigan Medical School in Ann Arbor said it would be important to ensure that the treatment didn't have unintended consequences, clearing carriers of more benign strains of MRSA only to open them up to recolonization with more dangerous strains causing an upswing in so-called community-acquired cases.
"We must be vigilant that our attempts to eradicate old strains do not facilitate the acquisition of strains that contain virulence determinants," Bradley wrote.
And Simor himself raised another possible concern, saying infection control specialists would need to watch to ensure the treatment didn't accelerate antibiotic resistance in MRSA strains.
"That remains a potential concern and a potential drawback," he said.
