I 

 CHAPTER XXVIII 



BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP 



(Continued) 



BACILLI INTERMEDIATE BETWEEN THE TYPHOID AND COLON 



ORGANISMS 



(Bacilli of Meat Poisoning and Paratyphoid Fever) 



THERE is an extensive group of Gram-negative bacilli which be- 

 cause of their morphology, cultural behavior, and pathogenic properties, 

 are classified as intermediate between the colon and the typhoid types. 

 The microorganisms belonging to this group have been described, most 

 of them, within the last fifteen years, but few of them have been fully 

 identified with one another. They have been variously designated as the 

 "hog-cholera group," "the enteritidis group," the "paracolon group" 

 or " paratyphoid group," because of the pathological .conditions with 

 which the chief members under investigation have been found associated. 



Attempts to systematize the group by the comparative study of a 

 large number of its members have been made, notably by Buxton 1 

 and by Durham, 2 and the work of these writers, based on cultural and 

 agglutinative studies, has added materially to our knowledge of these 

 organisms. 



The microorganisms of this group are morphologically indistinguish- 

 able from the colon and typhoid bacilli. They are Gram-negative and 

 possess flagella. Their motility is variable, but usually approaches 

 that of the typhoid bacilli in activity. They correspond, furthermore, 

 to the two other groups in their cultural characteristics upon broth, agar, 

 and gelatin. On potato, they vary, some of them approaching in deli- 

 cacy the typhoid growth upon this medium, others more closely 

 approximating the heavy brownish growth of B. coli. Indol is rarely 

 formed by them, though this has not been absolutely constant in all 

 descriptions. As a group, they are easily distinguished from Bacillus 



1 Buxton, Jour. Med. Res., N. S., iii, 1900. 2 Durham, Jour. Exper. Med., v, 1901. 



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