238 MANUAL OF BACTERIOLOGY. 



bonic plague. Besides these organisms, there are others 

 whose effects are usually more marked in a specific way 

 which sometimes form pus, as the bacilli of diphtheria, 

 tuberculosis, glanders and typhoid fever. 



Frequently two or more species of pyogenic bacteria will 

 be found associated. 



The table on page 239, quoted from Dowd, shows the fre- 

 quency of the occurrence of various pyogenic bacteria in 

 135 cases of different types of suppuration. 



The condition of the animal's tissues is of great impor- 

 tance in determining whether or not suppuration is to oc- 

 cur. It will be seen that we are repeatedly subjected to 

 infection with pyogenic bacteria, but that in most cases 

 suppuration nevertheless does not occur. The local condi- 

 tions have an important influence in determining infection. 

 Regions of hyperemia, edema, anemia or necrosis are 

 especially liable to suppuration, as are tissues which have 

 been bruised, lacerated, strangulated or otherwise dam- 

 aged. Furthermore, the general condition of the patient 

 is of great importance. Chronic diseases and conditions 

 of exhaustion or depression dispose to suppuration, and 

 the depraved condition of the tissues in diabetes renders 

 the sufferer from this disease especially liable to it. These 

 facts have already been enumerated in a previous chapter 

 (page 165). In the lower animals we find that it is often 

 very difficult to produce suppuration artificially with the 

 ordinary pyogenic bacteria. In rabbits the subcutaneous 

 introduction of staphylococcus pyogenes aureus frequently 

 fails to produce an abscess. Suppuration is likely to result, 

 however, if an irritant body like a piece of sterilized potato 

 or sterilized glass be introduced along with the bacteria. 



Pyogenic bacteria are most frequently introduced into 

 the body through the agency of injuries and wounds of 

 various sorts. They are very widely disseminated in 



