Observations on the Toxic Fractions of Scarlatinal Streptococci

Abstract

1. Among a series of strains of haemolytic streptococci from thirty-five cases of scarlatina in the first week of illness, fourteen were found to correspond with one or other of Griffith's serological types I, II, III and IV.2. Of these fourteen strains, twelve were selected for further examination and found to yield a true heat-labile exotoxin completely inactivated by heating for 30 min. at 100° C.3. The concentration of exotoxin in 0·5 per cent, glucose broth cultures was at a maximum after 96 hours' incubation, and thereafter on further incubation progressively diminished.4. No qualitative difference could be detected among the exotoxins from the different strains, the test criterion being the dermal reaction in Dick-positive persons.5. Cultures of organisms of the same or different serological type isolated from the same source and thereafter similarly treated yielded approximately equivalent amounts of exotoxin.6. Broth culture filtrates also contained an acid-insoluble toxic fraction, the concentration of which increased with the age of culture and which appeared to be identical with a similar acid-insoluble fraction derived from an alkaline extract of washed bacterial bodies.7. This acid-insoluble fraction was extremely heat-resistant, 3 hours' boiling at 100° C. being required for inactivation. In this respect the acid-insoluble fraction corresponded to the bacterial endotoxins.8. The acid-insoluble fractions from cultures of the same serological type produced equivalent skin reactions in susceptible persons.9. The acid-insoluble fractions from cultures of different serological types differed qualitatively as determined by skin reactions.10. The reaction to crude filtrate was found to be the sum of the reactions to the exotoxin fraction and to the acid-insoluble fraction present in the filtrate.