Methicillin-Resistant Staphylococcus aureus (MRSA)
Research
The National Institute of Allergy and Infectious Diseases (NIAID) funds basic and translational research with the ultimate goal to develop and promote enhanced diagnostics, better therapeutic treatments, and new vaccines that are effective against Methicillin-Resistant Staphylococcus aureus (MRSA). Given the increasing prevalence of MRSA in both hospital and community settings, it is important to understand how MRSA spreads, the factors that influence the severity of disease (virulence factors), and how best to treat MRSA infections. Virulence factors can include proteins that allow the bacteria to adhere to and colonize the host, to invade host cells, to inhibit the host immune response, and to poison and damage host cells.
Community-associated strains are notably effective at causing severe infections in otherwise healthy individuals and are different from the strains that cause hospital infections. As these strains begin to appear in hospitals where immunocompromised patients are at risk, it becomes increasingly important to understand how CA-MRSA can colonize and invade healthy people. Some current examples of NIAID-supported MRSA research are described below.
Virulence Associated Factors of Community-Associated MRSA (CA-MRSA)
Drs. Michael Otto and Frank DeLeo, and their colleagues at NIAID’s Rocky Mountain Laboratories (RML), recently described the essential role of the phenol-soluble modulin (PSM) protein family in CA-MRSA disease severity. These PSM proteins are able to destroy most immune cells, particularly white blood cells that help people fight off infection. While these proteins may not be the only virulence factors produced by CA-MRSA, they have been identified as major factors in the disease severity of CA-MRSA.
How CA-MRSA Spreads Among Households
Dr. Robert Daum, a researcher at the University of Chicago, is seeking to determine the best methods for containing, preventing, and treating CA-MRSA infections by understanding the circumstances that facilitate the transfer of CA-MRSA among household members. The study will determine how easily CA-MRSA is transferred from the initial infected person to other members within his/her household and at what rate household members become colonized or infected with CA-MRSA. The rate of CA-MRSA spread among household members will be compared to the rate of spread that occurs between a person infected with hospital-acquired MRSA (HA-MRSA), and other members within a household.
Strategies to Optimize the Use of Existing Antibiotics for MRSA Therapy
Two clinical trials are underway to define the optimal treatment for skin and soft tissue infections caused by CA-MRSA. CA-MRSA strains have remained more susceptible to commonly available antibiotics than hospital-associated MRSA strains; therefore, these trials will evaluate how effective off-patent antimicrobials are in treating uncomplicated cases of skin and soft tissue infections caused by CA-MRSA bacteria. Off-patent antimicrobials would be a cost-effective means of treating these infections and would alleviate the use of last-resort antibiotics such as vancomycin, which is essential for the treatment of hospital-associated MRSA.
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