366 TUBERCULOSIS AS A TYPE OF BACTERIAL DISEASE 



Fourthly, it is as regards growth and propagation a parasite. 



Fifthly, on inoculation it produces pathological cellular changes 

 distinct from the nodular new growths following inoculation of 

 acid-fast bacilli. In particular this is true, as far as is known at 

 present, in regard to the human organism. 



In a sentence, the acid-fast bacilli differ from the tubercle bacillus 

 in three main particulars, viz. : morphology of culture, conditions of 

 development (chromogenicity, rapidity of growth, range of tempera- 

 ture within which they flourish), and their feebler pathogenic proper- 

 ties. From these facts it follows that however great the degree of 

 similarity between these various acid-fast bacilli, and however much 

 it is possible by artificial cultivation to modify the morphology of 

 the various forms, there is sufficient difference to enable a differ- 

 ential diagnosis to be made if all the biological characters are 

 ascertained, and most of all the pathogenic properties. Hence the 

 importance of the inoculation test being applied to acid-fast and 

 tubercle-like organisms detected in milk or butter. 



As a simple method of differential diagnosis, Moeller suggests that 

 the smegma, sputum, or other secretion should be mixed with nutritive 

 bouillon, and kept at about 30 C. If in two or three days there is 

 a visible increase in the bacteria resistant to acids, it is certain that 

 it is not the genuine tubercle bacillus, which requires 37 C. Some- 

 times in sputum, mixed with certain nutritive media, the tubercle 

 bacillus increases at incubation temperature. This proliferation, 

 due in all probability to the importation of globulin-like substances 

 from the body, is, however, exceedingly small, and ceases altogether 

 after, at the latest, forty-eight hours ; whilst in the pseudo-tubercle 

 bacilli a persistent further proliferation takes place at 30. 



The pathological differences from Koch's bacillus are that inocu- 

 lation with acid-fast bacilli gives rise to 110 " giant cells," no epithe- 

 lioid cell clusters, and no tuberculous caseation. Nodular lesions 

 occur suggestive of tubercle, but according to Potet,* and Abbot and 

 Gildersleive f : (a) they constitute a localised lesion only, having no 

 tendency to dissemination, metastasis, or progressive destruction of 

 tissue by caseation ; (b) they tend to terminate in suppuration like 

 ordinary abscesses; (c) when occurring as result of intravenous 

 inoculation they appear in the kidney, rarely in the lung and 

 other organs; and (d) the form of granuloma set up is similar to 

 actinomyces. 



This group of organisms is one of considerable importance to the 

 milk bacteriologist, and in all investigations dealing with the tubercle 

 bacillus, or with milk and its products, it is essential that the bacilli 

 met with should be clearly differentiated from the tubercle bacillus. 



* Etude sur Us Bacttries elites Acidophiles (Potet, Paris, 1902), pp. 

 f The University of Pennsylvania Medical Bulletin, June, 1902. 



