Mouse study ties toxin to severity of blood infections.
For decades scientists have thought that S. epidermidis sepsis resulted from an overwhelming immune response to unchanging surface structures on the invading bacteria. Now, National Institutes of Health (NIH) scientists have identified an S. epidermidis toxin (PSM-mec) that is released into the bloodstream and contributes to sepsis. The investigators say this is the first time a toxin from S. epidermidis or closely related bacteria has been linked to sepsis.
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In tissue studies using S. epidermidis strains, the group found that the PSM-mec toxin helped the bacteria survive in human blood and resist attack by neutrophils, important immune system fighters. In a mouse model, the toxin significantly increased disease and stimulated the immune response, which worsened the septic infection.
The researchers say clinical studies are needed to assess whether PSM-mec affects sepsis in people and thus can be a target for therapeutics. They also are investigating whether related toxins found in methicillin-susceptible S. epidermidis and S. aureus have a similar function.