no CLINICAL BACTERIOLOGY AND HiEMATOLOGY 



PLAGUE 



The bacteriological diagnosis of plague should be made by an 

 expert; not because it is difficult, but because so much hinges 

 upon it — at least in this country. A brief account of the method 

 by which a practitioner who was unable to obtain expert help 

 might proceed may not be out of place. 



The plague bacillus is a short and rather thick rod which occurs 

 in vast numbers in the bubo, in the blood, and in the internal 

 organs. It does not stain by Gram's method, and when stained 

 by other processes it often exhibits a characteristic polar staining, 

 the ends of the bacillus being coloured deeply, whilst the inter- 

 vening portions remain colourless (Plate II., Fig. 4). It might 

 be mistaken for a diplococcus ; it could not be mistaken for 

 the pneumococcus (to which it has some resemblance), as that 

 organism stains by Gram. Degenerate forms which resemble 

 cocci, etc., often occur in cultures, but are seldom met with in 

 the body during life. 



The diagnosis may be made by an examination of fluid 

 aspirated from the bubo or of the blood. In bubonic cases the 

 former method should always be adopted, as the bacilli are 

 present therein in vast numbers, and generally in pure culture ; 

 the amount of fluid which has to be removed is very small, even 

 if cultures have to be taken. 



When this is not the case two films should be made in the way 

 already described, fixed and stained, the one by dilute carbol 

 fuchsin or Loffler's blue, and the other by Gram's method. If 

 the bacilli are present, they will appear as short oval rods which 

 may or may not exhibit the polar staining ; if the specimen has 

 been stained for the proper length of time (about two minutes), 

 most of them will do so, but in any case it will most likely be 

 present in a few. The Gram specimen will not show these rods ; 

 there may be a few pus cocci present as a secondary infection. 



The blood is examined by any of the methods to be described 

 subsequently, and a very careful search made, as the numbers of 

 the bacilli may be comparatively scanty. 



If a careful examination of stained films made from a bubo 

 does not show the organisms having the above characters, it is 

 probably safe to say that the case is not one of plague. 



