230 VETERINARY BACTERIOLOGY 



primary infections. It has not yet been proved ever to cause 

 suppuration alone in any of the domestic animals, but is not un- 

 common in pus, to which it gives a green or blue-green color. 

 In man it has been found in purulent otitis media, meningitis, 

 bronchopneumonia, infantile diarrhea, and generalized infections. 



Immunity. A true toxin is produced by virulent cultures. 

 Wassermann found 0.2 to 0.5 c.c. of this fatal for the guinea-pig. 

 An antitoxin has been prepared for this pyocyaneus toxin. An 

 endotoxin has also been demonstrated. A leukocytic poison, leU- 

 kocidin, and a hemolytic toxin, hemotoxin, have been differentiated. 

 Immunity has been experimentally produced by the injection of 

 killed cultures. 



Bacteriologic Diagnosis. The organisms may be most readily 

 determined by plating. The presence of a gram-negative bacillus 

 in pus in a stained mount constitutes presumptive evidence. 



Bacillus pyogencs sois 



This organism has been several times described from inflam- 

 matory suppurative processes in the hog. 



Morphology and Staining. The organism is a slender, non- 

 motile bacillus. It produces neither spores nor capsules. It 

 stains readily with the ordinary anilin dyes. It is gram-negative. 



Isolation and Culture. The organism may be readily isolated 

 in pure cultures immediately from the pus. It grows readily 

 on artificial media, particularly on coagulated blood-serum. 

 On this latter medium the small dry colonies form a slight area of 

 liquefaction immediately about them. 



Physiology. Growth occurs best at 37. No gas is produced 

 from dextrose. 



Pathogenesis. The organism has been found associated com- 

 monly with suppurative processes in the hog, particularly those 

 affecting the serous membranes lining the body-cavities. These 

 abscesses are generally encapsulated. 'Evidently they may arise 

 as metastatic infections, for they are sometimes distributed 

 throughout the body. The organism is pathogenic to rabbits 

 and mice, and may set up inflammatory processes in these ani- 

 mals closely resembling those of the hog. 



