DIPHTHERIA 269 



The diphtheria bacillus attacks glucose and lactose 

 with the formation of acid only, no gas (see Table, p. 

 292). As regards the production of acid, Neisser found 

 that during the first nine hours there is little or none ; 

 at the end of twenty- four hours a considerable quantity 

 has been formed, and the amount increases until the end 

 of the second day, after which the production ceases. 



The B. diphtheria is agglutinated by the serum of 

 patients and by a diphtheria serum, but the test is difficult 

 to apply on account of the coherence of the growth, is 

 somewhat erratic with different strains, and is of no 

 practical value in the diagnosis of the disease. For the 

 same reasons, the agglutination reaction is of little use 

 for the recognition of the organism and for distinguishing 

 it from the so-called " pseudo-diphtheria " bacilli. 



The Klebs-Loffler bacillus retains its vitality in cultures 

 for a month, and when dried for three or four weeks. 

 According to Welch and Abbot, it is destroyed in ten 

 minutes by a temperature of 58 C. It is readily destroyed 

 by antiseptics when in culture, but in the membrane it is 

 difficult to find an agent which will penetrate and kill 

 the bacilli beneath the surface. 



The diphtheria bacillus and its characters under culti- 

 vation have been described somewhat fully, because of 

 the importance of the identification of the organism as a 

 means of clinical diagnosis. As mentioned at the com- 

 mencement of this chapter, the clinical diagnosis of diph- 

 theria presents many difficulties, and considerable assist- 

 ance may be derived from a bacteriological examination. 

 The diagnosis is based on the presence or absence of the 

 Klebs-Loffler bacillus, either in smears, or in cultivations, 

 made from the membrane or secretion (see p. 292). This 

 method is of very real assistance in doubtful, and especially 

 in mild, cases, which clinically it may be very difficult to 

 decide whether they be diphtheritic or no. The mild 



