THE FIBRINOLYTIC ACTIVITY OF HEMOLYTIC STREPTOCOCCI

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Abstract
Broth cultures of hemolytic streptococci from patients are capable of rapidly liquefying normal human fibrin clot; the active principle is also contained in sterile cell-free filtrates of broth cultures. The degree of activity of filtrates parallels the activity of whole-broth cultures sufficiently closely to indicate that large amounts of the fibrinolytic agent are freely excreted into the surrounding medium. The occurrence of fibrinolysis is most strikingly observed when plasma or fibrinogen is mixed with active cultural material before clot formation. Under standard experimental conditions described, complete dissolution of human plasma clot (whole oxalated plasma + CaCl2) occurs in about 10 min.; complete dissolution of human fibrinogen clot (chemically isolated fibrinogen + thrombin) takes place in about 2 min. Of 28 strains of Streptococcus hemolyticus, isolated from patients with various manifestations of Streptococcus infection, broth cultures of all induced fibrinolysis; of 18 strains of animal origin, only 3 did so. Negative results were obtained with 38 other bacteria. Plasma of many patients recovered from acute hemolytic streptococcus infections, when clotted in presence of active cultures, is highly resistant to fibrinolysis. Furthermore, serum from patients whose plasma clot is resistant often confers on normal plasma clot an antifibrinolytic property. 1 example of the resistance possessed by blood of convalescent patients is presented. In contrast to the susceptibility of normal human fibrin clot to liquefaction by active culture, normal rabbit fibrin clot is totally resistant to dissolution when tested under comparable conditions. Its insusceptibility is manifest, provided the coagulum is composed of rabbit constituents; when human thrombin is used to clot rabbit plasma or fibrinogen in presence of active cultures, fibrinolysis is not prohibited. The role of thrombin in determining the resistance or susceptibility of rabbit fibrin to dissolution offers a suggestive approach to problems relating to the underlying mechanism.

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