Between one and three million people a year in the United States are diagnosed
with sepsis, and between 15 and 30% of them die. Severe
bacterial sepsis is characterized by an extreme immune response,
inflammation, reduced blood flow, clotting, and organ failure.
bacteria - typically skin dwellers - can infect
the bloodstream and cause a life-threatening condition known as sepsis. It is a significant health
concern for hospitalized infants, children and anyone with implanted
‘A Staphylococcus epidermidis toxin (PSM-mec) that is released into the bloodstream and contributes to sepsis has been identified by researchers.’
Methicillin-resistant strains of S. epidermidis
(MRSE) cause most sepsis cases. Notably, methicillin resistance rates in S. epidermidis
exceed those in the more-familiar S. aureus
(MRSA), and methicillin resistance makes MRSE infections difficult to treat.
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
(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.
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.