Bacteremia with viridans streptococcus can be observed after dental procedures, tooth extraction, tonsillectomy, especially if patients begin to eat immediately after these procedures. Enterococcal bacteremia and bacteremia associated with gram-negative bacteria can result from manipulations of the genitourinary tract, for example during bladder catheterization or cystoscopy, and urogenital operations. Staphylococci penetrate into the blood mainly during infection of intravenous catheters, during tooth extraction, respiratory and genitourinary tract infections, installation of a pacemaker, etc.
Pneumococci are a fairly rare causative agent of IE and are found mainly in pneumococcal pneumonia and alcoholism. Fungi usually enter the body when performing intravenous injections in drug addicts, as well as when suture material and artificial valves become infected during heart surgery. However, the presence of acne medication in the blood is not enough to cause disease. In practically healthy people, transient bacteremia also sometimes occurs. In order for microbes to exhibit a pathogenic effect and activation of infection to occur, a significant change in immunity is necessary, therefore the occurrence of IE is facilitated by various factors that reduce the reactivity of the body. illness, intoxication, overwork, surgery, pregnancy, childbirth, abortion, etc.
Bacteria circulating in the blood can attach to the endocardium, especially in altered areas. Impaired blood flow near the affected valves contributes to the formation of thrombotic deposits, which become a focus for the deposition of microorganisms. Microorganisms attach to the endothelium, after which theyare covered with fibrin deposits, forming the so-called vegetation.
The supply of nutrients into the growing season stops, and microorganisms enter a static growth phase. At the same time, they become less sensitive to the action of antibiotics, the mechanism of action of which is to inhibit the growth of the cell membrane. Highly pathogenic microorganisms quickly cause destruction of the valves and their ulceration, leading to the development of valve failure. Involvement of the chordae tendineae in the process leads to their rupture and the appearance of acute valve insufficiency.
Loose fibrin vegetations can break off from the valve and enter the bloodstream, causing embolism. If such an embolus comes from the right side of the heart, then thromboembolism of the branches of the pulmonary artery occurs. If the embolus has formed in the left side of the heart, then embolism of the vessels of the brain, spleen, kidneys, gastrointestinal tract, and limbs is observed. Fungal endocarditis is characterized by large emboli that can clog the lumen of large vessels. Simultaneously with the development of embolism, metastatic abscesses may develop.
The long course of infective endocarditis leads to activation of the immune system and the creation of a high titer of antibodies to pathogens. Circulating antigen-antibody complexes appear in the blood, which lead to the development of glomerulonephritis and cutaneous vasculitis.