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Emerging Staph Strains Increasingly Dangerous NIH release September 7, 2005 A study of how the immune system reacts to strains of antibiotic-resistant Staphylococcus
aureus bacteria — emerging strains that sicken otherwise healthy people,
or so-called “community-acquired” infections — has shown for the first time that
these strains are more deadly and better at evading human immune defenses than
more common S. aureus strains that originate in hospitals and other
health-care settings.
Scientists at NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, MT, and colleagues examined the ability of MRSA strains to cause disease in mice and avoid destruction by human white blood cells called neutrophils. Neutrophils, which typically ingest and then kill harmful bacteria, make up about 60 percent of all white blood cells and are the first line of defense against bacteria. Scientists know that community-acquired strains differ from hospital strains, but they don’t know why the community strains cause more serious infection in otherwise healthy people.
The work also identified specific S. aureus genes that potentially control the bacterium’s escape from neutrophils. Among thousands of S. aureus genes analyzed in the five different strains used in the study, the scientists identified a large group of genes whose role in helping spread infection is unknown. RML’s Frank DeLeo, Ph.D., the investigator who directed the study, and colleagues plan to determine if some of the unknown genes help promote disease. If they can learn which genes control the ability of S. aureus to evade and destroy neutrophils, their work could lead to new medical treatments. “Each day physicians around the world are stymied by the inability to effectively treat patients suffering from severe S. aureus infections,” says NIAID Director Anthony S. Fauci, M.D. “There is a critical need to develop new treatments against late-stage disease caused by antibiotic-resistant strains, and this promising work offers several new approaches.” According to the Centers for Disease Control and Prevention, “recent reports of ‘community-acquired’ MRSA infections raise concern … If MRSA becomes the most common form of Staphylococcus aureus in a community, it will make treatment of common infections much more difficult.” The April 7, 2005, issue of The New England Journal of Medicine refers in an editorial to “… an epidemic of MRSA in the community.” S. aureus strains acquired in health-care settings can be challenging to resolve because of antibiotic resistance, which limits the choices for treatment. But the situation can become more serious with the newer community-acquired strains, says Dr. DeLeo. “We do not know why cases of community-acquired MRSA infections are increasing, let alone how they flourish,” he says. But scientists do know the community strains can cause more severe forms of disease. Mild S. aureus infections such as impetigo, which typically forms small
blisters on the faces of children, or cellulitis, an inflammation of skin or
muscle tissue, can easily be treated and usually resolve in a matter of days.
But S. aureus disease also can be much more severe and difficult to
treat, affecting vital organs and leading to toxins poisoning the blood and infection
overwhelming the heart. One of the most severe types of disease is necrotizing
pneumonia, where bacteria destroy lung tissue.
News releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at http://www.niaid.nih.gov. NIAID is a component of the National Institutes of Health, an agency of the U.S. Department of Health and Human Services. NIAID supports basic and applied research to prevent, diagnose and treat infectious diseases such as HIV/AIDS and other sexually transmitted infections, influenza, tuberculosis, malaria and illness from potential agents of bioterrorism. NIAID also supports research on transplantation and immune-related illnesses, including autoimmune disorders, asthma and allergies. The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U. S. Department of Health and Human Services. It is the primary Federal agency for conducting and supporting basic, clinical, and translational medical research, and investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov. This is a NIH news release. The original version appears here Health News index | News index News index | RSS | Add to MyYahoo! Advertisements: Organic Apparel from Patagonia | Insect-repelling clothing |
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