PATHOGENIC BACTERIA 267 



Vaccines and Agents influencing the Opsonins 



Vaccines have been prepared of the etiological agents in : 

 Smallpox. 

 Tuberculosis. 

 Anthrax. 



Symptomatic anthrax. 

 Hydrophobia. 

 Practically all bacteria which produce endotoxins, such as, 



Msp. comma (Asiatic cholera). 



B. typhosus (Typhoid fever). 



M. pyogenes var. aureus (Pus infections). 



It should be remembered that only a few of the antibodies 

 above mentioned are of use as therapeutic agents. 



Factors which influence and modify Infections. The 

 conditions which modify an infection in the body by bacteria 

 or other microorganisms may be briefly stated as follows : 



(1) The virulence of the infecting agent. 



(2) The number of the infecting organisms. 



(3) The avenue of the infection. 



(4) The subject or individual infected. 



(i) Virulence. By this term is meant the ability of an 

 organism to produce disease. This property varies, and may 

 be increased or decreased. The virulence of a pathogenic 

 bacterium may be increased by passing it through a series of 

 susceptible animals, or growing it in celloidin sacs placed in 



