128 STUDY AND IDENTIFICATION OF BACTERIA 



cultivated from faeces we may find a diminution in number or absence of the colon 

 bacillus. This condition may be observed in infections with the organisms of 

 dysentery, cholera, typhoid, and paratyphoid. While its normal function is prob- 

 ably protective, yet the B. coli is an important pathogenic agent, it being fre- 

 quently the organism isolated from purulent conditions within the abdominal cavity, 

 especially in appendicitis and lesions about the bile ducts. It is particularly prone 

 to cause lesions of the bladder and pelvis of the kidney. In the treatment of colon 

 cystitis by vaccines of dead colon bacilli, brilliant results in opsonic therapy have 

 been obtained. 



Sir A. Wright thinks that certain cases of mucous colitis may be due to colon 

 infection and that vaccination may cure them. The colon bacillus is fully con- 

 sidered under the bacteriology of water. 



B. cloaca was isolated first from sewage by Jordan. It is, as a rule, 

 a rapid liquefier of gelatin, and in its reactions with sugars and litmus 

 milk resembles the colon bacillus. 



Where the gelatin liquefaction is slow or slight B. cloaca may be dis- 

 tinguished from B. coli by its gas formula which is about three times as 

 much CO2 as H, just the reverse of that of the colon bacillus. B. lactis 

 aerogenes is also often found in sewage. It is one of the causes of the 

 souring of milk. 



B. ACIDOPHILUS, B. BlFIDUS, B. BULGARICUS 



These are often termed the long rod group of lactic acid bacteria in 

 contradistinction to certain other Gram-positive bacilli which are short 

 and oval and which are confused with the so-called milk streptococci. 



The long rod group often forms chains and often shows metachromatic granules 

 which stain with Neisser's method. They are readily distinguished from Gram- 

 negative lactic acid producers, of which the type is B. lactis aerogenes, by their 

 Gram-positive staining. B. acidophilus often give the impression of a diphtheroid 

 in a Gram stained faeces smear. It is nonmotile and often shows polar granules. 

 Grows only at temperatures above 22C., op. 37C. It grows better anaerobically 

 than aerobically and then shows the clubbed involution characteristics of B. bijidus; 

 so that some consider these organisms the same, the morphology of B. bijidus being 

 the result of anaerobiosis. Original cultures are best made in i% glucose and i% 

 acetic acid bouillon. Some authorities consider B. bijidus the most important 

 representative of the large intestine flora. B. lactis acidi is less thermophilic than 

 B. acidophilus and coagulates milk which B. acidophilus does not do. Certain 

 polar granule bacteria, as B. granulosum, found in Yoghurt, are similar to B. acido- 

 philus but coagulate milk; no gas. B. bulgaricus is the type of the group and is 

 discussed under milk. 



Rodella thinks B. acidophilus, B. bijidus, B. gastrophilus and the Boas-Oppler 

 bacillus identical. B. bulgaricus is said to never show polar granules. B. bulgaricus 

 and the group of organisms similar to it found in buttermilk, etc., are widely used in 



