December 18, 2013
Drug-resistant infections from MRSA bacteria have moved increasingly from the nation's hospitals and nursing homes to the community at large, where they are striking otherwise healthy people in numbers far greater than government statistics suggest.
No drug-defying bug has proved more persistent than MRSA, none has caused more frustration, and none has spread more widely, according to a USA Today examination of federal records and dozens of studies and reports. Infections from the bacteria, formally known as methicillin-resistant Staphylococcus aureus, now strike often in the community, typically in settings where people are in close contact. It crops up among school children, soldiers, prison inmates?even NFL players.
In most cases, MRSA causes relatively minor skin infections that still can be treated effectively with certain antibiotics. But in some cases, the infections advance, destroying tissue and causing large abscesses that can require hospitalization. And when MRSA enters the bloodstream or attacks the lungs as bacterial pneumonia, it becomes especially dangerous?frequently fatal.
Hundreds of thousands of Americans are hospitalized with MRSA diagnoses each year and more than 20,000 die, federal data show. While MRSA was confined for decades to hospitals and other health care settings, new "community-acquired" MRSA strains have emerged since the 1990s, striking people who have had no contact with the medical system.
The movement of MRSA to new, community settings has confounded efforts by public health officials to develop prevention strategies and keep it from threatening vast new segments of the U.S. population.
"It's not about winning or losing the battle (against MRSA), it's that the battle is shifting," says Ramanan Laxminarayan, a Princeton University research scholar and director of the Center for Disease Dynamics, Economics & Policy. "You're seeing people who are young and healthy getting this (in the community), and it's very serious. ... And it's not picked up in the statistics."
To assess the evolving threat posed by MRSA, USA Today reviewed federal data on hospitalizations and infection rates, academic studies, and an array of government reports. Key findings:
Most cases go uncounted: Hundreds of thousands of MRSA cases a year are not included in government incidence estimates, because the Centers for Disease Control and Prevention track only the sliver of cases that escalate to life-threatening infections. The CDC reported 80,000 of those "invasive" cases in 2011, but there were more than 450,000 hospitalizations that year involving a MRSA diagnosis, according to hospital billing data collected by the U.S. Agency for Healthcare Research and Quality. And research suggests that millions more minor cases are resolved without hospital care.
Successes mask new threats: The medical community has made substantial headway reducing MRSA infections linked to hospitalization, cutting the worst of those infections anywhere from about 30% to upwards of 50% since 2005, according to a CDC-led study this year. But because that progress has fueled a drop in overall incidence rates for severe MRSA infections, it obscures the fact that there's been little progress in attacking the newer, community-based strains that have emerged. The CDC study found just a 5% drop in severe, community-acquired MRSA cases since 2005.
More infections in children: MRSA infections in youths aged three months to 17 years climbed an average of 10% a year from 2005-2010, according to another, CDC-led study this year. Perhaps more troubling, many of the infections in children are community-based strains of the bacteria, which can pass from kid to kid by physical contact or sharing contaminated objects. "With community strains getting more prevalent among children, that's going in a direction we don't want to see," says Scott Fridkin, who heads the CDC's surveillance of antibiotic resistant illnesses in health care settings.
A patchwork control plan: Health officials credit the reduction in health care-related MRSA infections partly to initiatives that emphasize better hospital hygiene and careful maintenance of catheters and other devices that can let bacteria into the body. But they've struggled to develop strategies for reducing community-acquired MRSA. Most states, like the federal government, don't track where and when those cases are occurring, so less is known about how to combat the illnesses. And, while it's relatively easy to change conduct in a hospital environment, it's harder to alter behavior in the public at large.
"The challenge now is in the community," says Robert Daum, an infectious disease physician and founder of the University of Chicago's MRSA Research Center. "With all due respect to our public health authorities, they made the transition in their minds very slowly that the epidemiology of MRSA had shifted. They don't have programs that track the epidemiology carefully in the community. So we are left with a community problem that has been largely unaddressed."
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