DIPHTHERIA. 217 



membrane, or the like, must be present for diphtheria to 

 result from infection with true diphtheria-bacilli from a case 

 of diphtheria. 



Method and Significance of the Bacteriologic Diag- 

 nosis of Diphtheria. Every case of inflammation of the 

 throat should be examined with regard to the presence of 

 diphtheria-bacilli, and, if these be found, the case should be 

 treated from both the medical and the hygienic standpoint 

 as one of diphtheria (just as every case of diarrhea with 

 comma-bacilli in the stools should be treated as one of 

 cholera), as the mildest case of diphtheric angina may give 

 rise to severe infection. 



For diagnostic purposes, simple microscopic examination 

 of the mucus or of the membrane in stained cover-glass 

 preparations will suffice in some cases. Double staining, 

 by the method of M. Neisser, which is so characteristic for 

 preparations made from cultures, has not proved entirely 

 reliable in the study of original preparations. If the prepara- 

 tions, stained single or double, are not entirely convincing, 

 cultural investigation must be additionally undertaken. 



A small portion of the diphtheric membrane is removed 

 with forceps, sterilized by heat, or, directly, with a 

 strong platinum loop ; or a sterile swab of cotton or a 

 sterile bit of sponge is rubbed upon the suspected surface 

 to be examined, and six or eight strokes are made upon a 

 plate of Loffler's blood-serum. Should this not be avail- 

 able, from three to five tubes of blood-serum or glycerin- 

 agar, solidified in slants, are successively inoculated. Plates 

 and tubes are placed in the thermostat at a temperature of 

 37 C. (98.6 F.) according to M. Neisser best at a 

 temperature of 34 C. (93.2 F.) or 35 C. (95 F.). 

 In the first streak or in the first tube inoculated the 

 colonies are too dense, and they coalesce ; in the last they 

 are isolated, and these are then examined further. It is 

 recommended also that the membranes, before being 

 smeared, be rinsed for several' minutes in two per cent, solu- 

 tion of boric acid, whereby a considerable number of the 

 saprophytic bacteria, accidentally present, are removed, so 

 that a separation of the individual colonies is brought about 

 in the first inoculation-smears. After six or eight hours 

 impression-preparations are made from the serum-plate. 

 If these display the typical collections described (p. 208), 

 then a positive diagnosis can be made. A negative diag- 



