Fibrinolytic Activity of Hemolytic Streptococci and Other Microörganisms

Abstract

The fibrinolytic activity of hemolytic streptococci has been extensively studied by Tillett and Garner. 1 According to these authors, only hemolytic streptococci, with the exception of some strains of staphylococci, produce fibrinolysin. Cultures of Streptococcus viridans, Streptococcus non-hemolyticus, enterococcus, pneumococcus, and other microörganisms proved to be ineffective. These findings were recently corroborated by Schmidt. 2 The object of our investigations was to ascertain the significance of the composition of the culture-medium for the production of the fibrinolysin.

The respective broths (with plain meat-infusion broth, pH 7.4 as a base), were inoculated and incubated at 37°C. for 18 hours. The cultures were centrifuged and the supernatant fluid tested for fibrinolytic activity according to the technique of Tillett and Garner. 1

The plasma used for the experiments was prepared by mixing 10 cc. of human blood with 1 cc. of a 2% potassium oxalate solution. The blood was shaken thoroughly and centrifuged. For the demonstration of the fibrinolysin, the supernatant fluid of the culture, in the amount of 0.5 cc., was mixed with 1 cc. of a 1:5 dilution of human plasma; then 0.25 cc. of a 0.25% calcium chloride solution in normal saline was added, the tubes shaken thoroughly and kept at 37°C. The results were read at various intervals.

The influence of the glucose-concentration of the meat-infusion broth upon the production of the fibrinolytic substance by hemolytic streptococci was first studied. In Experiment I, 3 strains of hemolytic streptococci were incubated for 18 hr. at 37°C. in meat-infusion broth containing 2, 0.4, 0.08, and 0.016% glucose. The supernatant fluid of the respective cultures was tested for fibrinolytic activity.

As can be seen in Table I, strain 693 produced fibrinolysin in 2% and 0.4% glucose broth, but not in 0.08% and 0.016% glucose broth.