188 VETERINARY BACTERIOLOGY 



belonging in common to all the organisms of a group are more 

 easily remembered than when learned separately for each species. 

 A classification may be based upon the character of the disease 

 produced; that is, be pathologic. Such a classification is open 

 to the objection that very different types of infection may be pro- 

 duced under different conditions by the same or closely related 

 organisms. Certain pus cocci, for example, may produce erysip- 

 elas, wound suppuration, septicemia, pyemia, or local infection, 

 and inflammation of almost any organ of the body. On the other 

 hand, infections having similar clinical characters may be pro- 

 duced by very different organisms. A bacteriologic classification 

 is based upon resemblances in morphologic, physiologic, and cul- 

 tural characters. 



The following classification, in the main bacteriologic, will be 

 used in the differentiation of the various groups of known micro- 

 organisms, exclusive of the protozoa, that are of pathogenic 

 veterinary interest. 



Principal Groups of Pathogenic Microorganisms 



I. True bacteria. 



A. Cells spherical, cocci. 



1. Non-specific pyogenic organisms. Non-specific pyogenic coccus 

 group (1). 



2. Causing specific infections. Specific coccus group (2). 



B. Cells rod-shaped. Bacilli. 



1. Non-specific pyogenic forms. Non-specific pyogenic bacillus 

 group (3). 



2. Usually associated with specific infections, 

 a. Aerobic or facultative anaerobic. 



(1) Non-spore producing, 

 (a) Not acid fast. 



+ Gram positive. 



1. Diphtheria group (4). 



2. Bacillus pseudotuberculosis group (5). 



3. Swine erysipelas group (6). 

 + + Gram negative. 



1. Glanders group (7). 



2. Intestinal group (8). 



3. Hemorrhagic septicemia group (9). 



4. Fowl diphtheria group (10). 

 (6) Acid fast. Acid fast group (11). 



(2) Spore producing. Anthrax group (12). 



