Disturbance in the function of the blood platelets, which is to form a blood clot when the vessel wall has been wounded, to close the gap and staunch the loss of blood. Healing of the wound is concluded by coagulation of the blood and growth of new wall cells. Sometimes blood platelets form a thrombus when there is no wound in the vessel wall. The platelets then cling to the wall of a vessel which has been altered by a condition such as atherosclerosis, and are potentially able to cause cardiac infarction or a stroke. People with extensive calcification of the blood vessels, post-operative patients and bed-ridden patients are at blood poisoning (septicaemia) Presence and growth of pathogenic bacteria in the blood. Whenever there is bacterial inflammation that the body cannot suppress, bacteria may enter the bloodstream. Particularly after surgery (reduced resistance), a relatively harmless inflammation (of the bladder (cystitis), for example) may develop into sepsis. The bacteria enter the blood in two ways, indirectly via the lymphatic system (causing inflammation of the lymph ducts and/or lymph nodes) or directly, by penetrating capillary walls. The presence of bacteria in the blood is known as bacteriaemia, and is often associated with high fever and cold shivers. If the bacteria are rendered harmless before they can multiply, recovery soon takes place; sepsis sets in if they are allowed to multiply. The patient becomes seriously ill within a few hours, with high fever, often over 40°C. The bacteria in the blood can reach any part of the body and cause inflammation. In serious cases a condition like paralysis occurs in the walls of all blood vessels, causing them to dilate, leading to shock (known as septic shock). Sepsis must always be treated quickly by all possible means, because the patient could die as a result of severe inflammation reactions. Large quantities of antibiotics should be administered by infusion. In the case of septic shock, extra fluids should be given intravenously.