154 DIPHTHERIA AND PSEUDODIFHTHERIA. 



New Orleans, it has been possible to make examinations of 

 the swabs themselves by making cover-glass preparations 

 from the same even two or three days after they were pre- 

 pared, and in a great majority of the cases come to a positive 

 or negative conclusion, verified later clinically and also bac- 

 teriologically, by cultures made from these same swabs. 



It is essential for these examinations that the cultures from 

 the throats of suspected cases be made before antiseptics have 

 been applied to the throat, or, if that is not possible, the cult- 

 ures should be made at an interval of at least two or three 

 hours after such applications, as otherwise the antiseptics 

 may have acted on the bacilli on the surface of the membrane 

 and destroyed them or greatly inhibited their growth. 



PSEUDODIPHTHERIA. 

 Bacillus Pseudodiphtheriae. 



Another source of error in the application of this method 

 comes from the pseudodiphtheria bacilli which are found in 

 cultures, and which greatly resemble the virulent Bacillus 

 diphtherice, but have no pathogenic power. 



These pseudobacilli are of two kinds : 



I. It is not possible to separate the first kind from the 

 true diphtheria bacilli either by morphology or cultural 

 properties. When injected into the lower animals they are 

 non-virulent, because they secrete no toxin. 



II. The second kind, in the opinion of the author, are 

 very improperly so-called, for they are not diphtheria bacilli, 

 and can with little difficulty be differentiated from true diph- 

 theria bacilli by their appearance, mode of staining, and their 

 cultural properties. 



Differential Diagnosis. The method of staining suggested by 

 Neisser, as mentioned in the beginning of the chapter, is 

 applicable especially to the recognition of the second form of 

 pseudobacilli. In culture media containing sugars B. pseudo- 

 diphtherise will not produce acid, while B. diphtheria? will 

 produce acid in media containing dextrose, levulose, or mal- 

 tose. 



