Community-acquired MRSA moves in on hospitals
The traditional distinction between hospital- and community-acquired methicillin-resistant S. aureus (MRSA) infection may soon become insignificant. At Friday's session “Staphylococcus aureus: What's New?”, Daniel J. Diekema, FACP, discussed the epidemiological issues that are changing the face of MRSA, along with options for treating and preventing infection.
Community-acquired MRSA has traditionally affected younger, otherwise healthy patients, along with having a different DNA footprint and different antimicrobial resistance than hospital-acquired infection. But it's now becoming more common in the hospital setting.
“I'm not sure how much longer we're going to be able to call it 'community-acquired' MRSA,” Dr. Diekema said. He pointed to studies showing that outbreaks have turned up in neonatal and obstetrics units and that community-acquired MRSA is now a major cause of nosocomial bacteremia. “We have to be on the lookout for changing presentations, new syndromes,” Dr. Diekema said. “Almost anywhere in the country now, you need to think about these community-acquired MRSA strains.”
For treatment of MRSA bloodstream infection, vancomycin is still the standard. “There's no data suggesting that anything is better,” Dr. Diekema said. For refractory MRSA and S. aureus infection, new drugs, such as daptomycin and linezolid, are available, but the ideal regimens have yet to be determined. In addition, Dr. Diekema said, the best way to treat skin and soft-tissue infections due to MRSA remains an open question.
For prevention, identification and decolonization of nasal S. aureus carriers, or targeted decolonization, is one suggested method. But there are problems with this approach, Dr. Diekema said.
For starters, S. aureus colonization is common, affecting 32% of the population according to one study. And decolonization is only a temporary fix. According to Dr. Diekema, 30% to 40% of people recolonize within 90 days. “In my view, there are two reasons to seek S. aureus nasal carriers,” Dr. Diekema said: to prevent infection in a high-risk carrier, or in others by isolating the carrier.
Dr. Diekema recommends decolonization in carriers only to decrease recurrent infection or during outbreaks, and said that the issue of preoperative decolonization to reduce surgical site infection is not resolved. Physicians may want to consider decolonization in high-risk patients before major cardiothoracic or orthopedic surgery, but the evidence doesn't support routine decolonization or decolonization in general surgical patients, Dr. Diekema said.
Seeking out and isolating MRSA carriers, however, may soon become common practice. Some hospitals and organizations, including the VA and the Institute for Healthcare Improvement, are recommending or mandating active surveillance for MRSA among hospitalized patients.
“That's coming,” Dr. Diekema said. “It may already be here for some people.”
But although this approach will detect more colonized patients, it can also have unwanted consequences, Dr. Diekema pointed out. Research shows that isolated patients have increased incidence of depression and anxiety, dramatically reduced contact with health care workers and increased rates of noninfectious adverse events, such as falls. Dr. Diekema stressed that physicians must be alert to these possibilities as the issue of universal screening develops.
“This approach is gaining steam,” he said. “You need to know how it might affect your patients.”
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