COMPARATIVE STUDIES UPON THE PSEUDO-DIPHTHERIA, OR 



HOFMANN BACILLUS, THE XEROSIS BACILLUS, AND 



THE LOFFLER BACILLUS. 



By D. H. Bergey, M. D., 

 First Assistant, laboratory of Hygiene, University of Pennsylvania. 



The group of pseudo-diphtheria bacilli and the xerosis 

 bacillus are now of very great interest because, by their 

 marked similarity to the Loffler bacillus in many of their 

 morphological and biological characters, they lead to un- 

 certainty in the diagnosis of true diphtheria by micro- 

 scopic examination alone. The pseudo-diphtheria bacilli 

 are sometimes found in cases of true diphtheria in connec- 

 tion with the Loffler bacillus, but more frequently in cases 

 of benign throat affections, either alone or in connection 

 with staphylococci and streptococci. The xerosis bacillus 

 is found very frequently on the conjunctiva of healthy 

 persons, where it apparently gives rise to no disturbances. 

 It is also found in the nasal cavity and the throat of per- 

 sons suffering from benign inflammations of the lining 

 membrane of these cavities. Both of these groups of 

 organisms have also been found upon the skin of various 

 portions of the body, without at times apparently pro- 

 ducing any appreciable symptoms ; at other times they 

 have been found in various skin diseases, in the genito- 

 urinary organs of healthy persons, as well as in various 

 diseased conditions of these organs. 



The pseudo-diphtheria bacilli were first described by 

 Loffler (i) and by von Hofmann-Wellenhof (2), who re- 

 garded them as being non-virulent forms of the Loffler 

 bacillus. 



Roux and Yersin (3) demonstrated that the Loffler bacil- 

 lus possessed great variations in virulence, sometimes 

 being non-virulent, and they were also of the opinion that 



(19) 



