Resistant Staph Infections Increasing in Hospitals

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Antibiotic resistant staph infections that are normally found in the general community are increasingly showing up among hospital outpatients treated in emergency departments, surgical centers and physician offices, raising the risk that inpatients could become infected.

Researchers from Princeton University analyzed data from over 300 microbiology labs in the United States and found that the incidence of outpatients with Methicillin-resistant Staphylococcus aureus, also known as MRSA, has increased seven-fold while hospital-associated infections have remained stable or declined due to improved infection control measures. This poses a risk to inpatients because many resources, such as imaging and laboratory equipment, are used by both sets of patients.

"We found during 1999-2006 that the percentage of S. aureus infections resistant to methicillin increased more than 90 percent, or 10 percent a year, in outpatients admitted to U.S. hospitals," the authors wrote in the report published in the December journal Emerging Infectious Diseases. "This increase was caused almost entirely by community-acquired MRSA strains, which increased more than 33 percent annually."

In addition, the researchers found two new strains of the bacteria, adding to concerns about the continuing change that allows the superbug to become resistant to antibiotics.

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Staph skin infections generally start as small red bumps that resemble pimples or insect bites. The bacteria can penetrate the skin through a wound or small opening and cause a deeper infection. Methicillin is a type of antibiotic that was once able to kill the staphylococcus virus. Some strains, including MRSA, have become resistant, and stronger drugs are needed to eliminate the infection. About 20,000 people in the United States die each year from MRSA infections.

Community-associated strains of the MRSA virus (CA-MRSA) are typically less virulent than hospital-associated infections (HA-MRSA) and more susceptible to wider variety of antibiotics, but they can still cause significant illness and death. The infection can be acquired in any public place, including schools and fitness centers, and now account for more than 60% of all acquired staph infections, according to the CDC.

"MRSA has generally been a significant problem only in hospitals," said Eili Klein, the report's lead author and researcher at Resources for the Future. "The movement of community-associated strains into the hospital also points to the urgent need for rapid tests that can identify the strain of MRSA"

Risk factors for acquiring community associated MRSA include young age and others with an immature or weakened immune system, participation in contact sports, sharing towels or athletic equipment, handling unclean surfaces, living in crowded or unsanitary conditions, and association with health care workers that may unknowingly bring the virus into the community.

"Our findings have implications for local and national policies aimed at containing and preventing MRSA,” the researchers write, concluding their report. “Infection control policies should take into account the role that outpatients likely play in the spread of MRSA and promote interventions that could prevent spread of MRSA from outpatient areas to inpatient areas.”

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