BACILLUS DIPHTHERIA 523 



as bacillus Hoffmann!, were avirulent. This would confirm the impres- 

 sion gained, we believe, by most experienced laboratory workers that 

 a true Hoffmanni can be distinguished with considerable certainty from 

 a Kleb-Loeffler bacillus by morphological examination alone, and that 

 its significance is probably that of a frequently present saprophyte of 

 the throat and pharynx. The studies of Goldberger, Williams and 

 Hachtel also indicate that in examining for diphtheria carriers it is 

 best not to confine oneself either to the nose or throat, but that cultures 

 should be taken from both places in every case. 



Bacteria Similar to Bacillus Diphtherias. BACILLUS HOFFMANNI 

 (Pseudodiphtheria bacillus). Hoffmann- Wellenhoff, 1 in 1888, and, at 

 almost the same time, Loeffler, 2 described bacilli which they had culti- 

 vated from the throats of normal persons and in several instances from 

 those of diphtheritic persons, which were in many respects similar to true 

 B. diphtherias, but differed from this chiefly in being non-pathogenic for 

 guinea-pigs. These organisms were at first regarded by some observers 

 as merely attenuated diphtheria bacilli. More recent investigations, 

 however, prove them to be unquestionably a separate species, easily 

 differentiable by proper methods. They differ from B. diphtherias in so 

 many important features, moreover, that the term "pseudodiphtheria 

 bacillus" is hardly an appropriate one for them. 



Morphology. Bacillus Hoffmanni is shorter and thicker than 

 Bacillus diphtherias. It is usually straight and slightly clubbed at one 

 end, rarely at both. Stained with Loeffler's blue it occasionally shows 

 unstained transverse bands; unlike B. diphtherias, however, these bands 

 hardly ever exceed one or two in number at most. In many cultures the 

 single transverse band x gives the bacillus a diplococcoid appearance. 



Staining. Stained by Neisser's or Roux's method, no polar bodies 

 can be demonstrated. The bacillus forms no spores, is non-motile, and 

 possesses no flagella. 



Cultivation. On the usual culture media B. Hoffmanni grows more 

 luxuriantly than B. diphtherias, developing even in first isolations from 

 the human body upon the simple meat-extract media. On agar plates 

 its colonies are larger, less transparent, and whiter than are those of 

 true diphtheria bacilli. In fluid media there is even clouding and less 

 tendency to the formation of a pellicle than with B. diphtherias. A posi- 

 tive means of distinction between the two is given by the inability of B. 

 Hoffmanni to form acid upon various sugar media. The differentiation 



1 Hoffmann-Wellenhoff, Wien. med. Woch., iii, 1888. 



2 Loeffler, Cent. f. Bakt., ii, 1887. 



