Sepsis (/ˈsɛpsɨs/; from the Greek σῆψις: the state of putrefaction and decay) is a potentially deadly medical condition characterized by a whole-body inflammatory state (called a systemic inflammatory response syndrome or SIRS) caused by severe infection. Septicemia (or septicaemia or septicæmia [ˌsɛptɨˈsi:miə]) is a related medical term referring to the presence of pathogenic organisms in the bloodstream, leading to sepsis. The term has not been sharply defined. It has been inconsistently used in the past by medical professionals, for example as a synonym of bacteremia, causing some confusion.Sepsis is caused by the immune system's response to a serious infection, most commonly bacteria, but also fungi, viruses, and parasites in the blood, urinary tract, lungs, skin, or other tissues. Sepsis can be thought of as falling within a continuum from infection to multiple organ dysfunction syndrome.Common symptoms of sepsis include those related to a specific infection, but usually accompanied by high fevers, hot, flushed skin, elevated heart rate, hyperventilation, altered mental status, swelling, and low blood pressure. In the very young and elderly, or in people with weakened immune systems, the pattern of symptoms may be atypical, with hypothermia and without an easily localizable infection. Sepsis causes millions of deaths globally each year.Sepsis is usually treated with intravenous fluids and antibiotics. If fluid replacement isn't sufficient to maintain blood pressure, vasopressors can be used. Mechanical ventilation and dialysis may be needed to support the function of the lungs and kidneys, respectively. To guide therapy, a central venous catheter and an arterial catheter may be placed; measurement of other hemodynamic variables (such as cardiac output, mixed venous oxygen saturation or stroke volume variation) may also be used. Sepsis patients require preventive measures for deep vein thrombosis, stress ulcers and pressure ulcers, unless other conditions prevent this. Some might benefit from tight control of blood sugar levels with insulin (targeting stress hyperglycemia). The use of corticosteroids is controversial. Activated drotrecogin alfa (recombinant activated protein C), originally marketed for severe sepsis, has not been found to be helpful, and has recently been withdrawn from sale.