Bacteremia

BACTEREMIA (from bacteria and Greek haima—blood), the presence of bacteria in the blood, the phenomenon of the transport of microbes via the bloodstream, characteristic of many infectious diseases. Bacteremia represents one of the methods of spreading an infectious agent throughout the body and generalizing an infection by way of metastasis, occurring significantly more often than previously assumed. Bacteriological examination (culture) of the blood in many infectious diseases reveals bacteria in the bloodstream, and furthermore (besides the long-known bacteremia in miliary tuberculosis and typhoid fever), in a number of cases of infectious diseases that would seem to have a local character, such as gonorrhea, tuberculosis, diphtheria, etc. In the latter, bacteremia, apparently, is not a rarity (in surgical tuberculosis, Braudes and Man discovered Koch's bacillus in 45% of examined cases); in pneumonia, one can quite often isolate the pneumococcus from the blood. Erysipelas, according to data by Petruschky, is also often accompanied by streptococcal bacteremia. Bacteremia in itself does not always provide a basis for prognostic conclusions, since in some diseases (typhoid fever) it appears in every case, being a necessary link in the development of the given infectious process. As for the fate of microbes circulating during bacteremia, a portion of them apparently perishes from the bactericidal properties of the blood, and partly they are captured by the reticulo-endothelium of the spleen pulp, bone marrow, and liver. Furthermore, they are eliminated by the kidneys and liver, which leads to the occurrence of bacteriuria and bacteriocholia. Upon experimental introduction of low-virulence microbes into the bloodstream of an animal, they very easily and quickly disappear from the blood: already after 5-10 minutes, a blood culture often yields a negative result, and after half an hour to an hour, the microbes, as a rule, disappear from the bloodstream. Simultaneously with this, one can detect their appearance in the urine and bile. Bacteremia can take place not only as a symptom of some specific form of an infectious disease. Bacteria, apparently, can slip into the blood in the case of some disruption of the barriers separating the internal environment of the organism from the bacterial flora of its various regions (gastrointestinal tract, respiratory, urogenital). Thus, Bertelsmann established that in all cases of fever after catheterization, the blood turns out to be non-sterile. In the case of an inflammatory process affecting the intestine, conditions can be created for the penetration of bacteria from among the permanent inhabitants of the gastrointestinal tract. As shown by experiments on animals (Ficker), bacteremia of intestinal origin can be caused even with a healthy intestinal wall under the condition of starvation of the animal or during excessive muscular fatigue. As for very young animals, the cells of their intestinal mucosa present such poor protection against bacteria that even in a completely healthy organism, microbes can freely penetrate into the bloodstream. Apparently, frequent entry portals for the agent causing bacteremia are the tonsils, especially those affected by a chronic inflammatory process. In those cases where bacteria, upon entering the bloodstream, are not only carried by it throughout the vascular system of the organism but also cause a general reaction of the latter, one speaks of septicemia (see). The tendency to produce septicemic forms is especially pronounced in streptococci and staphylococci, which, during their bacteremic spread, usually produce local purulent foci, causing so-called pyemia (see). Lit.: Seitz A., Wesen d. Infektion (Kolle W., Kraus R., Uhlenhuth P., Handbuch d. pathogenen Mikroorganismen, B.I, Lief. 12, 1927); Jochmann G., Die Bedeutung d. intravitalen u. postmortalen Nachweise v. Bakterien im menschlichen Blute, Ergebn. d. allgemeinen Pathologie usw., B. X. E. Totarinov.