358 TUBERCULOSIS AS A TYPE OF BACTERIAL DISEASE 



The B. psmdo-tuherculosis (Pfeiffer) resembles B. eoli, and occurs as short, small 

 bacilli, cylindrical, and with round ends. Its manner of growping is singly, or in 

 couples or chains ; sometimes filamentous forms and long chains occur in 

 bouillon culture. It stains by alkaline Loffler's methyl-blue, and also by Gram's 

 method (Klein). It is non-motile. In bouillon, in twenty-four hours a well-marked 

 granular cloudiness appears, and small flocculi float through the hquid. Imperfect 

 pellicle after several days' growth. No general turbidity. On gelatine the growth 

 resembles B. coli, but the colonies are more circumscribed and granular, and later, 

 they become tuberculated. Growth is slow, and the colonies become more opaque, 

 whiter, and less spread out than B. coli. No gas is formed in gelatine shake cultures. 

 There is no liquefaction of gelatine. On agar minute grey-white flat colonies appear. 

 Stroke and stab cultures are similar to B. coli, but not so luxuriant. There is 

 hmited growth on potato, which forms a thin layer with crenated thicker margin of 

 a whitish-yellow colour. It grows well in milk, but leaves it unaltered. Patho- 

 genesis — Guinea-pigs inoculated subcutaneously with a small quantity of culture die 

 in a few weeks. Their organs are found to be studded with yellow-white nodules 

 containing the bacillus in pure culture. These nodules develop more rapidly than 

 true tuberculosis, but do not contain any giant cells. If fed with food contaminated 

 with this organism, similar nodules develop in the walls of the intestine and mesenteric 

 glands. Klein believes that : " The presence of the B. pseudo-tuberculosis in milk may 

 probably play a part in causing pseudo-tuberculous disease in the human subject." 



Klein found this bacillus present in 2 out of 5 samples of London 

 milk,* and in 8 out of 100 samples of country milk delivered in 

 London.f DeMpine found that out of 450 samples of milk, lesions 

 produced by pseudo-tubercle bacilli were met with four times. It 

 seems not unlikely that this group of bacilli includes several varieties 

 bearing a close general resemblance to each other, but possessing 

 slightly different properties. They gain access to milk in all 

 probability by some accidental contamination. The milk itself 

 remains unaltered in appearance, though it becomes alkaline. As 

 regards differential diagnosis, it may be said that the pseudo-tubercle 

 bacillus is not acid-fast, nor is it similar to JB. tuberculosis in morpho- 

 logical or cultural characters. The pathological changes set up by 

 it, and which form its chief claim to be considered as in any way 

 related to tuberculosis, differ from that disease in showing an absence 

 of giant cells in the nodules, absence of the true tubercle bacilli, 

 copious presence of the pseudo-tubercle bacilli, and a more rapid 

 development of disease. 



Acid -FAST Bacilli allied to the Tubeecle Bacillus 



We may here suitably consider the group of organisms 

 morphologically and tinctorially similar to the bacillus tuberculosis. 

 This group is known as that of the acid-fast bacilli, on account of 

 the fact that in staining by the Ziehl-Neelsen method (see p. 459) 

 these organisms possess, like the tubercle bacillus, the power of 



* Report of Local Government Board, 1899-1900, p. 360, and 1900-1901, p. 332. 

 t Jour, of Hygiene, 1901, vol. i., p. 83. 



