Research Provides Clue About How Bacteria and Infection Spread

A new study by researchers at Children’s and the University of Washington School of Medicine finds Staphylococcus aureus bacteria may produce a substance that prevents people from being able to fight off infection.

A new study by researchers at Children’s and the University of Washington School of Medicine finds Staphylococcus aureus bacteria may produce a substance that prevents people from being able to fight off infection. “Staph” bacteria are responsible for a growing number of hospital and community-acquired diseases including skin, pneumonia, bone and bloodstream infections. The study was published in the May 1, 2007 issue of Journal of Infectious Diseases.

Globally, Staphylococcus infections have increased over the past few decades. There are also newer, antibiotic-resistant strains occurring with increased prevalence, so these research findings may shed important light on human immune response. Staphylococcus aureus, in particular, can commonly cause pneumonia. In this study, nasal passages of mice were infected with staphylococcal bacteria, causing symptoms resembling those of human pneumonia. Staphylococcus aureus was found to produce the protein staphylokinase, which appears to undermine immune response by breaking down blood clots the immune system produces to help “wall off” bacteria to keep it localized within the body.

According to Craig E. Rubens, MD, PhD, chief of pediatric infectious disease at Seattle Children’s Hospital Research Institute, these data suggest that producing staphylokinase may be a mechanism by which Staphylococcus aureus increases virulence, leading to enhanced invasive infection. “The Staphylococcus aureus protein staphylokinase surprisingly binds to a secondary protein in the lung. This encourages faster breakdown of blood clots, which we believe promotes bacterial spread from the lung to other parts of the body,” said Rubens. “This may provide clues to how bacteria start infections, how they spread, and how to improve immune defense mechanisms. Better understanding of how Staphylococcus aureus causes infection and exploits the immune system may result in improved prevention and treatment.”

Ongoing research at Seattle Children’s Hospital Research Institute will continue to study Staphylococcus aureus infections in children. Other Children’s researchers included lead investigator Marissa H. Braff and Amanda L. Jones, and Shawn J. Skerrett from the University of Washington School of Medicine.

For a complete copy of the study, please visit:

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Seattle Children’s Hospital, Foundation and Research Institute together deliver superior patient care, advance new discoveries and treatments through pediatric research, and raise funds to create better futures for patients. Consistently ranked as one of the top 10 children’s hospitals in the country by U.S. News & World Report, Seattle Children’s Hospital specializes in meeting the unique physical, emotional and developmental needs of children from infancy through young adulthood. Through the collaboration of physicians in nearly 60 pediatric subspecialties, Seattle Children’s Hospital provides inpatient, outpatient, diagnostic, surgical, rehabilitative, behavioral, and emergency and outreach services to families from around the world.

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