BACILLUS _DIPHTHERL 523 



the city of Detroit, and found that 0.928% harhored bacilli identical 

 morphologically with the Klebs-Loeffler bacillus. This figure is rather 

 lower than those of some other investigators, but would indicate, as 

 the writers stated, that there were from 5,000 to 6,000 diphtheria car- 

 riers in the city of Detroit. 



Of 19 cultures isolated from 19 of the carriers, only 2 were virulent, 

 which would indicate that only 0.097% of the people examined carried 

 organisms capable of producing disease. An interesting further point 

 is that the bacillus Hoffmanni was present in at least 41.9% of over 

 2,000 individuals examined, and that 47 cultures, morphologically 

 identified as Bacillus Hoffmanni, were avirulent. This would confirm 

 the impression gained, we believe, by most experienced laboratory 

 workers that a true Hoffmanni can be distinguished with considerable 

 certainty from a Klebs-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 Diphtherise. 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. diphtheria, but differed from this chiefly in being non-patho- 

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

 observers as merely attenuated diphtheria bacilli. More recent inves- 

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

 easily differentiate by proper methods. They differ from B. diph- 

 theriae in so many important features, moreover, that the term "pseu- 

 dodiphtheria bacillus" is hardly an appropriate one for them. 



Morphology. Bacillus Hoffmanni is shorter and thicker than Ba- 

 cillus diphtheria. 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 fa number at most. In many cultures 

 the single transverse band gives the bacillus a diplococcoid appearance. 



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



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



