Sepsis (from the Greek. Σήψις, “Decomposition”) or blood poisoning is a medical term referring to a potentially fatal condition which involves a general inflammatory response, known as systemic inflammatory response syndrome (SIRS), caused by an infection. Current treatment of Sepsis is through the use of antibiotics and intravenous fluids.
Sepsis is SIRS triggered by an infection. Often, but not always, there is bacteria in the blood of the affected patient, which has spread from a local infection or directly due to an infected bloodstream. However, the presence of bacteria in the blood is not in itself synonymous with sepsis.
Sepsis can be divided into three levels of severity: sepsis, severe sepsis and septic shock. The definition of sepsis (SIRS + infection) is such that it does not include conditions which are life-threatening. In practice, therefore, sepsis is used – somewhat incorrectly – to refer to severe sepsis, namely sepsis causing low blood pressure, impaired oxygenation of the blood, or other organ failure. Septic shock is a severe sepsis condition where blood pressure cannot be normalized quickly despite administration of intravenous fluids.
Sepsis is commonly caused by bacteria but in rare cases even fungi, parasites (such as malaria) or viruses. Sepsis due to a bacterial infection usually originates in the lungs (pneumonia), the kidneys (pyelonephritis), abdominal organs, the meninges (meningitis) or in bones and joints. Sometimes no other origin of the infection is found than the blood itself.
The disease mechanism is complex and not fully known. During sepsis, the body reacts through a general inflammatory response to molecules from the microorganism that have caused the infection. Depending on the type of bacterium, these molecules may be lipoteichoic acid or lipopolysaccharide (LPS) molecules. The body’s immune system secretes a variety of inflammatory neurotransmitters, cytokines and chemokines, which activate immune cells and affect blood vessels, as well as the endocrine system. These effects occur at both cellular and organ levels and include, among other things, increased blood vessel permeability, causing fluid leakage from the bloodstream. This lowers the blood pressure resulting in an impaired oxygen supply to several viral organs. This can in turn lead to confusion, and temporary loss of urine production by (renal failure). Activation of the immune system results in fever and the immune cells release bactericidal agents, which can also damage the blood vessels and impair circulation. Sepsis can also cause deterioration in cardiac and lung function, whilst the cells, platelets, blood components and coagulation factors responsible for vascular coagulation can be activated causing both bleedings and blood clots.
Symptoms may vary from patient to patient but often involve fever, severe malaise, weakness and confusion. There may also be symptoms due to a local infection. It is not unusual for nausea and vomiting or loose faeces to occur.
Treatment should begin as soon as possible and includes antibiotics and intravenous fluids. The antibiotics kill the bacteria and the fluid maintains the blood pressure. Sometimes additional oxygen is needed for sufficient oxygenation of the blood and organs. In very severe cases, drugs to increase blood pressure are also needed.