Antihuman Fibrinolytic Streptococci

Abstract

Tillett and Garner 1 have recently described a hitherto unknown antihuman fibrinolytic function of hemolytic streptococci. This function is demonstrable with S. hemolyticus of human origin, but is not demonstrable with apparently identical environmental or veterinary streptococci. Since the lytic factor is not active against normal rabbit fibrin, many of the results of streptococcus research on rabbits are presumably not applicable to human pathology. We have, therefore, extended the Tillett-Garner tests to include plasma-clots from other animal species. The object of these tests was to find a laboratory animal suitable for a direct study of the topographical distribution 2 and in vivo fibrinolytic function of S. hemolyticus.

The S. hemolyticus used in these tests were 2 human (C 203 and K 96) and 2 veterinary (P 454 and K 158 E) strains kindly furnished by Dr. Lancefield of the Rockefeller Institute. To these we have added a number of local strains, one of special interest being J 1, originally isolated from a clinical case in San Francisco. This strain contains the human-diagnostic carbohydrate fraction recently described by Lancefield. 3

The fibrinolytic tests were made by the Tillett-Garner technic. To 1 cc. 20% oxalated plasma was added 0.25 cc. 0.25% CaCl₂-solution, followed by 0.5 cc. 18-24 hour broth culture of the microorganism to be tested. A semi-opaque agar-like clot is usually formed within 10 minutes. In nonlytic or negative tests no softening of this clot is demonstrable after 24 hours incubation at 37°C. In positive tests, beginning (+), well advanced (++), or complete (+++) liquefaction is noted within from 30 minutes to 2 hours.