366 DIPHTHERIA 



organism from being the diphtheria bacillus. From these facts, 

 and from what has been stated with regard to attenuated 

 diphtheria bacilli, it will be seen that an absolute decision as to 

 the nature of a suspected organism may in some cases be a 

 practical impossibility. It may be that some of the " diphtheroid " 

 organisms cultivated have really been non-virulent diphtheria 

 bacilli. The bearing of this on the practical means of diagnosis 

 will be discussed below. 



The term " pseudo-diphtheria bacillus " is often restricted by 

 present writers to an organism frequently met with in the throat. 

 This organism, which is also known as Hofmann's bacillus, merits 

 a separate description. 



Hofmann's Bacillus Pseudo - Diphtheria Bacillus. This 

 organism, described by Hofmann in 1888, is probably the 



same as one observed by 

 Loffler in the previous 

 year, and regarded by him 

 as being a distinct species 

 from the diphtheria bacil- 

 lus. The organism is a 

 shorter bacillus than the 

 diphtheria bacillus, with 

 usually a single unstained 

 septum running across it, 

 though sometimes there 

 may be more than one 

 (Fig. 122). The typical 

 beaded appearance is rarely 

 seen, and the reaction with 

 Neisser's stain is not given. 

 FIG. 122. Pseudo-diphtheria bacillus It grows readily on the 

 (Hofmann's). Young agar culture. same media as the diph- 



Stained with thionin-blue. x 1000. theria bacillus, but the 



colonies are whiter and 



more opaque. It does not form acid from glucose or other 

 sugars, and is non-pathogenic to the guinea-pig. Involution 

 forms may sometimes be produced by it. It is usually a com- 

 paratively easy matter to distinguish, this organism from the 

 diphtheria bacillus. 



Hofmann's bacillus is of comparatively common occurrence in 

 the throat in normal as well as diseased conditions, including 

 diphtheria ; it seems to be specially frequent in poorly nourished 

 children of the lower classes. Cobbett found it 157 times in an 

 examination of 692 persons examined, of whom 650 were not 



