CHAPTEE XVIII. 



BACTERIA PRODUCING DIPHTHERITIC INFLAMMATIONS- 

 BACILLUS DIPHTHERIA BACILLUS NECROPHORUS 

 BACILLUS DIPHTHERIA AVIUM. 



A NUMBER of anatomical types of inflammation, such as serous, 

 fibrinous, purulent, hemorrhagic, and diphtheritic, are distinguished 

 in pathology. The microorganisms most commonly causing purulent 

 inflammations have been described in the two preceding chapters. 

 Some of the most important organisms causing diphtheritic inflam- 

 mations will now be considered. A diphtheritic inflammation is one 

 marked by extensive necrosis, either due in the beginning to chemical 

 or physical influences (acids, alkalies, heat, cold), or resulting, at an 

 early stage, from the toxins of the pathogenic invading and multi- 

 plying organisms. In either case an area of tissue containing numerous 

 necrotic cells is formed; generally on the surface adjacent to the 

 necrotic zone there is a hyperemic one with dilated vessels, with an 

 abundant transudate and numerous migrated leukocytes. Diphtheritic 

 inflammations tend to form pseudomembranes, which are grayish 

 white, yellowish white, dirty gray, or if mixed with a great number of 

 erythrocytes, dark gray or dirty brown in color. These membranes, 

 when removed artificially, or when shed in the natural course of the 

 necrosis, leave a raw, ulcerated, often bleeding surface. 



BACILLUS DIPHTHERIA. 



Occurrence and Pathogenesis. Diphtheritic inflammations occur in 

 man and the domestic animals. In man diphtheria is generally a 

 disease of the tonsils, pharynx, and larynx, although it may also occur 

 in accidental or operative wounds. It is caused by the bacillus of 

 diphtheria. 



Morphology. This bacillus, as found in. recent diphtheritic inflam- 

 mations or obtained from pure cultures raised on Loeffler's blood- 

 serum mixture, shows the following morphologic features: The 

 bacillus varies considerably in length from 1 to 6 micra; the majority 

 being about 3 micra. It is from 0.3 to 0.8 of a micron thick. 

 In shape it is frequently slightly curved, and in very rare cases 

 cylindrical. It is generally thickened at one end or more rarely 

 at both ends, making it either club-shaped or dumb-bell-shaped. 

 When it forms chains they are always short. On division and multi- 

 plication the bacilli have a tendency to separate immediately at the 



