PATHOGENIC PROPERTIES OF YEASTS 123 



By injecting into the peritoneal cavity of a guinea pig a culture 

 of S. pastorianus and examining what happened, by removing a little 

 of the peritoneal fluid at regular intervals, the same author, 1 observed 

 a phagocytosis of the yeasts. They were demonstrated to be alive, how- 

 ever, by means of inoculation. After from 2 to 3 hours they were 

 broken up in the interior of the leucocytes and at the end of from 10 

 to 11 days they were proven to be dead by means of inoculations into 

 beer wort. If, however, in place of an ordinary yeast, a pathogenic 

 yeast be used, such as S. subcutaneous tumefaciens, the same phe- 

 nomena are observed with the single difference that phagocytosis 

 is more energetic. This commences after a sort of lag, at first by the 

 polynuclear leucocytes and finally the mononuclears; often a cell is 

 observed which has been ingested by many leucocytes. On the other 

 hand, a yeast may defend itself by surrounding itself by a mucilag- 

 inous envelope. A battle between the yeasts and the leucocytes 

 ensues. But finally the leucocytes triumph and at the end of two or 

 three days all the yeast cells find themselves ingested. 



It may be inferred, then, that ordinary yeasts do not exhibit a 

 pathogenic phase and that pathogenic yeasts themselves provoke 

 only a light of doubtful intoxication. According to Casagrandi, 2 

 and Demme 3 a yeast, Crypt, ruber, caused an acute enteritis in young 

 infants. The active agent was probably a secondary cleavage prod- 

 uct from the milk in which it was secured. 



If one summarizes the numerous observations of secondary in- 

 fections by yeasts and the diverse lesions of the skin, mucous mem- 

 branes or internal organs, the cases are rare where these fungi exhibit 

 any actual pathogenic r61e. Blastomycoses thus seem to be excep- 

 tional diseases and not so very frequent. 4 



That we drink with wine large numbers of yeasts might indicate 

 their harmlessness. For a long time we have attributed curative prop- 

 erties to beer yeasts toward such infections as furunculosis. Ser- 

 gent 5 has noticed an antiseptic action of yeasts against infections with 

 Staph. pyogenes aureus. Perhaps these properties find their explana- 

 tion in the existence of a toxin recently demonstrated by Hayduck, 

 Fernbach and Vulqium. It has been shown in the preceding chapter 

 that, according to certain authors, yeasts secrete a toxin endowed 



1 Skchiwan, Ann. Past. Inst. 13, 1899. 



2 Casagrandi, O. Saccharomyces ruber. Ann. d'Ig. sperm. 1898. Vok. 7 

 and 8. 



3 Demme, R. Saccharomyces ruber. Ann. de microg. 1889 and Annali d'Ig. 

 sperm. 1897, Vol. 7. 



4 Duval and Laederich. Arch, de Protistology 3. 



6 Sergent, E. Levure de biere et suppuration Ann. Inst. Past. 17, 1903. 



