Invasion of the bloodstream, after surgery or infectious disease, by microorganisms—typically gram-negative (see gram stain) bacteria—and the toxins they release. The latter trigger immune responses and widespread coagulation in blood vessels. High fever, chills, weakness, and sweating are followed by a drop in blood pressure. Multiple infections are often present, requiring broad-spectrum antibiotics as well as drainage of foci of infection. Without immediate treatment, septic shock follows, with a mortality rate over 50percnt. Invasive technology and antibiotic-resistant bacteria in hospitals have made septicemia more severe and more common. Seealso bacteremia.

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