464 A MANUAL OF BACTERIOLOGY 



(4) B. acidi lactici. Non-motile. Ferments adonitol, but not 

 sucrose and dulcitol. Var. Grunthal, motile. 



In Group VI of the Typhoid-Colon bacteria they place : 



(5) B. (lactis) aerogenes. Found in the intestine of nurslings 

 and in milk. Much like B. coli, but is non -motile. It differs from 

 B. coli by not fermenting dulcitol, by fermenting sucrose and 

 adonitol, and by giving the Voges-Proskauer reaction. According 

 to Harden and Walpole, 1 its action on glucose differs from that of 

 B. coli, more alcohol being produced and formed at the expense of 

 that part of the molecule of the sugar which in the B. coli fer- 

 mentation yields acetic and lactic acids. 



The B. aerogenes, which may be classed among the capsulated 

 bacilli, is occasionally pathogenic, causing peritonitis. 2 In these 

 circumstances it is capsulated, but the capsule is difficult to stain. 

 It seema probable that the B, capsulatus of Pfeiffer is identical 

 with this organism. 



(6) B. cloacce (Jordan). Met with in sewage. In general 

 characters it much resembles B. coli, but is non -motile and pro- 

 duces more gas (75 per cent.) from glucose and liquefies gelatin 

 in four or five to thirty days. Like B. aerogenes, saccharose is 

 always fermented and the Voges-Proskauer reaction is positive, 

 but neither dulcitol nor adonitol is fermented. 



Clinical Examination 



(1) The appearance and odour of the pus are often character- 

 istic. Smears of the pus show small bacilli, which are decolorised 

 by Gram's method. 



(2) The organism may be isolated by plating on gelatin, agar, 

 litmus lactose agar, Conradi-Drigalski agar, or by the use of 

 neutral red or bile-salt media (see "Water"). The isolated 

 organism must be tested as to its morphology, motility, Gram 

 staining, action on gelatin, indole production, curdling of milk, 

 and fermentation reaction. 



(3) An agglutination reaction may likewise be tried, but if 

 negative is of little value, as there are so many varieties of the 

 colon bacillus, and one variety may not be agglutinated by the 



1 Journ. of Hygiene, vol. v, 1905, p. 488 ; Proc. Roy. Soc. Lond., B, 

 vol. xxvii, 1906, p. 399. 



2 See Churchman, Johns Hopkins Hosp. Bull, vol. xxii, 1911, p. 116. 



