PATHOGENIC BACTERIA. 313 



fatal. Probably they may occur with typhoid fever in mixed and second- 

 ary infections. Characteristic lesions have not yet been observed. The 

 bacilli have been found in the blood, spleen, liver, gall-bladder and 

 urine. Like typhoid and colon bacilli they are motile, have flagella, are 

 not stained by Gram's method and do not liquefy gelatin. They ferment 

 dextrose and maltose, producing acid and gas. They do not ferment 

 lactose. Milk at first becomes acid, later it becomes alkaline, and is not 

 coagulated. On potato a slight visible growth occurs. Media contain- 

 ing neutral red become yellow, as with B. coli communis, but more 

 slowly, and the red color sometimes returns. In respect to the fermen- 

 tation of saccharose and the formation of indol reports differ; both are 

 usually negative. The blood of the patient agglutinates the bacilli. But, 

 as among the closely related members of this group mutual reactions are 

 sometimes seen, this test is not to be considered invariable. 1 Several 

 bacilli allied to the above are known. The bacillus enteridis of Gaertner 

 is a related form which has been found in cases of meat-poisoning. 



Bacillus lactis aerogenes (Bacillus aerogenes). A ba- 

 cillus having a form similar to that of the colon bacillus, 

 described as being larger and plumper. In the main its 

 properties are similar to those of the colon bacillus. Its 

 colonies are more circumscribed and elevated. It is also 

 non-motile. It coagulates milk more rapidly than the 

 colon bacillus. It produces gas upon potato more rapidly 

 than the colon bacillus, and more abundantly. It was de- 

 scribed by Escherich, who also described the colon bacillus, 

 assigning the bacillus lactis aerogenes rather to the upper 

 part of the small intestine, and the colon bacillus to the 

 lower portion. According to Kruse, the bacillus lactis aero- 

 genes and its relatives differ from the bacillus coli com- 

 munis chiefly in lacking motility. Like the colon bacillus 

 it has been found many times in the urine in cystitis. See 

 also B. acidi lactici, page 227. 



Bacillus dysenteriae (Shiga). A bacillus with rounded 

 ends, of the size and shape of typhoid and colon bacilli, 



'Gushing, Bulletin Jo/ins Hopkins Hospital, July-August, 1900; 

 Strong, Ibid., May, 1902; Johnstone, Hewlett, Longcope, American 

 Journal Medical Sciences. August, 1902; Libman, Buxton, Journal 

 Medical Researcli. Vol. VIII., 1902. 



