SEPSIS, a term in medicine denoting infection of a wound or collection of fluid or dead material by bacteria usually conveyed from without. Etymologically the term signifies putrefaction and at first it was thought that the wound was putrefying as dead animal material putrefies. This view was found to be too narrow under the advances made by knowledge in bacteriology and the term now embraces conditions differing widely in pathology and severity.
In one group, that to which the names sapraemia and septic intoxication are given, the condition is in reality putrefactive. Where dead protein material is contained within a cavity and putrefactive bacteria gain access to it, these bacteria multiply, use the protein as food and form therefrom waste products that are poisonous to animals. These poisons are absorbed into the patient's body by the veins and lymphatics in the walls of the cavity and produce fever, wasting, sweating, etc., characteristic of the toxic condition. But the essential point is that they are the products of putrefactive bacteria which cannot live in the circulating blood. Hence the factory of the poisons is physio logically outside the body and removal of the dead protein by drainage or washing out the cavity at once stops the formation of the poisons, they are no longer absorbed, the symptoms dis appear and the patient recovers.
In the other group the general conditions may be identical, apparently, but the bacteria concerned are not those of putre faction; they are pathogenetic and capable of living within the blood and tissues of the patient. Here the factory of the poison is physiologically within the body and removal of dead protein by drainage or washing out the cavity is incapable of any note worthy influence on the course of the disease. This group is known as septicaemia or septic infection with a subgroup pyaemia if the bacteria concerned give rise to foci of suppuration. The micro-organisms concerned in this group are chiefly streptococci and staphylococcus pyogenes aureus.
Together the two groups form the condition of "blood poison ing" and it is clear that the second group is infinitely the more dangerous. Diagnosis between them is not always easy but
sapraemia does not occur in the absence of a relatively large cavity with much putrescible material therein, whereas a minute scratch, as in conducting a post-mortem examination, may suffice for the introduction of streptococci that occasion a fatal septi caemia. Nevertheless, with such primary conditions as a wound at the bottom of which there is pent up blood clot or exudation, a collection of fluid in the abdomen or a joint cavity after opera tion or a uterus after parturition, particularly if it has not con tracted well and still contains blood clot or portions of afterbirth, the symptoms may depend on either sapraemia or septicaemia and diagnosis can only be made by noting the results of clearing out the infected cavity, and bacteriological examination of the con tents of the cavity and the patient's blood.
The pathology of sapraemia needs no further remark than that the bacteria concerned are mainly the proteus group (see BACTERIOLOGY) and that they are introduced into the putrescible material from without by instruments, hands, etc. But the septi caemic group requires more consideration for in many instances the source of the infection is not obvious.