A Hemolytic Substance in Pneumococcus Culture Broth.

Abstract

In the course of previous studies, 1 , 2 it was found that type I pneumococcus culture broth contained a substance which resembled the hemotoxin described by Cole 3 , 4 and later by Avery and Neill. 5 Unlike the substance described by Cole, which was contained within the cells and was only set free by their dissolution, the hemolytic substance in the culture broth appeared, in some cases, as early as 4 hours after incubation was begun. The titer of the lytic substance, as indicated by the amount of culture broth required to produce an appreciable amount of hemolysis of 1 cc. of 1% washed sheep cells, was usually greatest after from 16 to 24 hours’ incubation.

Culture broth of a group-IV pneumococcus strain, comparatively avirulent in its present form but capable of having its virulence raised by animal passage, and of a completely avirulent, atypical pneumococcus strain, No. 189, isolated from a horse which died during immunization with the standard type-I strain, No. 5, also contained the hemolytic substance.

The hemolytic substance in the culture broth, like that of Cole, is thermolabile and is destroyed by heating for 30 minutes at 55° C. Its activity is diminished by standing at cold room temperature and also, in a much shorter time, at 37° C.

Red cells, stroma, and leucocytes absorb the substance from the culture broth. The substance is also absorbed from the culture broth by shaking with animal charcoal and alumina. Shaking alone, however, greatly reduced the lytic power of the culture broth.

Normal horse serum has an inhibitory effect on the hemolytic power of the substance, while pneumococcus immune serum has a much more marked effect, which is apparently species rather than type specific.