28 



INFECTION 



are occasionally parasitic lead a saprophitic existence in the soil 

 or water, and yet may invade the body, and produce disease: the 

 tetanus and malignant oedema bacilli are examples of this group. 

 Those bacteria that are purely parasitic are only known as they exist 

 in the tissues of the infected host, and have no outside existence 

 at all. 



Kruse's Scheme Illustrating the Action of Various Parasitic 



Bacteria. 



Parasitic 

 Bacteria. 



Occasionally paras- 

 itic. Such as the Tetan- 

 us bacillus. 



B 



Always parasitic only 

 found in the lesions of 

 disease. Such as the 

 B. tuberculosis. 



1. Local infection due to the 

 ability of the organism to 

 take on unrestricted growth. 



a. Surface inflammation, 

 boils; staphylococci. 



b. Surface inflammation 

 with extension of con- 

 tinuity; erysipelas 

 streptococci. 



c Surface infection with 

 marked toxin products; 

 diphtheria. 



d. Deep focal inflamma- 

 tion', tubercles. 



2. General infection of un- 

 restricted growth. 



a. By continuous infec- 

 tion; glanders. 



b. Metastases, as in py- 

 ccmia. 



c. By universal rapid 

 growth and invasion, 

 as in sepsis and an- 

 thrax. 



