580 PATHOGENIC MICROORGANISMS 



conditions, fatal infections may occur. Such cases, however, are still to 

 be regarded as depending more upon the low resistance of the individual 

 attacked than upon the great pathogenicity of B. pyocyaneus. 



Many domestic animals are susceptible to experimental pyocyaneus 

 infection, chief among these being rabbits, goats, mice, and guinea- 

 pigs. Guinea-pigs are killed by this bacillus with especial ease. Intra- 

 peritoneal inoculation with a loopful of a culture of average virulence 

 usually leads to the death of a young guinea-pig within three or four days. 



Toxins and Immunization. Emmerich and Low have shown that 

 filtrates of old broth cultures of B. pyocyaneus contain a ferment-like 

 substance which possesses the power to destroy some other bacteria, 

 apparently by lysis. They have called this substance " pyocyanase " and 

 claim that, with it, they have succeeded in protecting animals from 

 anthrax infection. During recent years pyocyanase has been employed ' 

 locally for the removal of diphtheria bacilli from the throats of convales- 

 cent cases. Broth-culture filtrates evaporated to one-tenth their volume 

 in vacua are used for this purpose. 



Pyocyanase is exceedingly thermostable, resisting boiling for several 

 hours, and is probably not identical with any of the other toxins or 

 peptonizing ferments produced by B. pyocyaneus. 



The toxins proper of B. pyocyaneus have been the subject of much 

 investigation, chiefly by Wassermann. 1 Wassermann found that filtrates 

 of old cultures were far more poisonous for guinea-pigs than extracts 

 made of dead bacteria. He concludes from this and other observations 

 that B. pyocyaneus produces both an endotoxin and a soluble secreted . 

 toxin. The toxin is comparatively thermostable, resisting 100 C. for a 

 short time. Animals actively immunized with living cultures of B. pyo- 

 cyaneus give rise in their blood serum to bacteriolytic antibodies only. 

 Immunized with filtrates from old cultures, on the other hand, their 

 serum will contain both bacteriolytic and antitoxic substances. The 

 true toxin of B. pyocyaneus never approaches in strength that of diph- 

 theria or of tetanus. Active immunization of animals must be done 

 carefully if it is desired to produce an immune serum, since repeated 

 injections cause great emaciation and general loss of strength. Specific 

 agglutinins have been found in immune sera by Wassermann 2 and 

 othei-s. Eisenberg 3 claims that such agglutinins are active also against 

 some of the fluorescent intestinal bacteria. 



1 Wassermann, Zeit. f. Hyg., xxii, 1896. 2 Wassermann, Zeit. f. Hyg., 1902. 

 3 Eisenberg, Cent. f. Bakt., 1903. 



