Abstract
Since but 17% of all local strains of Streptococcus hemolyticus originally isolated from superficial infections of man are demonstrably thrombolytic 1 by the Tillett-Garner plasma-clot technic, 2 we have retitrated these strains by their more delicate serum-free fibrin-clot method. This retitration has raised the percentage of demonstrably fibrinolytic strains to 25%.
It is of basic interest to determine whether or not the remaining 75% have or have not a demonstrable antihuman fibrinolytic capacity. To determine this we have again retitrated all local strains, using a modification of the Tillett-Garner enzyme-concentration method.
Since at least 75% of the fibrinolysin in a 24-hour broth culture of S. hemolyticus is usually lost as a result of filtration, enzyme-concentrates were prepared from unfiltered broth cultures. To prepare such a concentrate, 20 cc. unfiltered 24-hour veal-infusion broth culture is added to 60 cc. 96% alcohol, both culture and alcohol being ice-cold at the time of mixing. The resulting mixture is allowed to stand at refrigerator temperature for at least an hour. The precipitate is then collected by centrifugation, and rapidly dried in a vacuum desiccator.
To make the fibrinolytic test, the crude precipitate is suspended in 1 cc. buffered salt-solution and freed from undissolved residue by centrifugation. The resulting centrifugate usually has a fibrinolytic titer at least 20 times that of the original broth-culture, which is generally equivalent to at least 80 times that of the broth-filtrate.
Retitration of 123 local strains of S. hemolyticus originally isolated from superficial infections of human beings has raised the percentage of recognizable fibrinolytic strains to 35%. About oneeighth of all apparently non-fibynolitic strains of S. Izemolyticzu from infections in man, therefore, have a demonstrable fibrinolytic potential, recognizal~le 1iy the 20-fold enzyme-concentration technic.
By the same enzyme-concentration technique the percentage of strains of S. hemolyticus from infections of lower animals positively lytic for hunnan fibrin has been raised from 7% to 22%. None of the 40 local strains of S. viridans, however, has shown a demonstrable anti-human fibrinolytic capacity.
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