Published November 20, 2014
The antibiotic-resistant microbe MRSA may be slowing its pace after rampaging through hospitals for years, researchers from the U.S. Centers for Disease Control and Prevention said Tuesday.
From 2005 to 2008, surveillance data from nine metropolitan areas showed an overall decline of 28 percent in severe infections with MRSA (methicillin-resistant Staphylococcus aureus) contracted in healthcare settings.
"We are encouraged by the findings," said CDC's Dr. Alexander Kallen, whose study is published in the Journal of the American Medical Association.
Although the data aren't nationally representative, he said they bolster earlier studies and are "very good evidence that invasive MRSA infections are decreasing."
Versions of Staphylococcus aureus resistant to the penicillin-like antibiotic methicillin were first discovered in the UK in the early 1960s; since then, the multidrug-resistant bacterium has cropped up and become a problem around the world, especially its persistent spread in hospitals.
In 2005, researchers estimate the bug caused severe infections in nearly 95,000 Americans, killing more than 18,500 of them.
The new study, drawing on surveillance data for a population of about 15 million people in nine metropolitan areas, looked only at infections in which the bacteria had invaded a sterile part of the body, such as the blood and joints.
Of the more than 21,500 cases identified, more than three-quarters were in people who were hospitalized or had been in recent contact with the healthcare system.
Kallen said the number of people who had acquired the bug somewhere other than a healthcare facility was too small to provide good data.
Over the four-year study period, the occurrence of severe MRSA infections that showed up while a patient was hospitalized dropped by nine percent each year, from an initial rate of about one in 10,000.
In non-hospitalized patients, the rate dropped by nearly six percent annually.
"Overall, it's good news," Dr. Daniel J. Diekema of the University of Iowa, an expert in infectious diseases, told Reuters Health.
"But before we get too self-congratulatory about reducing MRSA rates, we need to remember MRSA is only one type of Staph," said Diekema, who wrote an editorial about the new findings. He noted that MRSA accounts for less than one in 10 hospital infections.
At this point, nobody knows why the rates are falling. One possibility is that infection prevention efforts are paying off, said Diekema.
Over the past decade, hospitals have introduced several measures aimed at preventing the spread of infectious disease, such as requiring staff to wash their hands with soap before inserting a catheter into a patient.
CDC's Kallen said this was probably one of the most important points, and he recommended patients always make sure that nurses and doctors wash their hands prior to providing care.
Some hospitals also test patients specifically for MRSA when they admit them, a procedure that may cost as much as $45 per patient.
To ensure hospitals' limited resources are well spent, said Diekema, "it would be nice if we knew more about what prevention measures have led to this decline."
Journalist Maryn McKenna, who published a book about MRSA earlier this year, said the findings were no reason to stop worrying about the superbug. (See Reuters Health story of May 14, 2010.)
"We already know that if we don't pay close attention to it, it burgeons," she told Reuters Health, adding that the new study was the first strong signal that prevention programs might work.
"It would be a really bad time to relax," she said. "It's a good time to say instead, let's figure out what's working."