46 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



very thorough search ; if no bacilli are seen, make several more 

 films and examine them. When you see a group of bacilli, 

 examine it carefully, noting each characteristic and comparing 

 it with those described above. 



The beginner is strongly recommended to procure a series of 

 slides of diphtheria bacilli from a bacteriological laboratory, and 

 to study them carefully. 



Hoffmann's bacillus (Plate I., Fig. 2) is frequently met with 

 in throat cultures. It is about as long as the short form of 

 diphtheria bacillus, but decidedly plumper, and is more uniform 

 in shape and size. These bacilli stain uniformly and deeply. 

 They exhibit the same arrangement, and are often grouped in 

 pairs. Clubbed forms do not occur. 



The diphtheria bacilli which occur in films made direct from the 

 swab are similar to those seen in cultures, but are often thicker ; 

 they may stain uniformly, and clubbed forms are rare. It is 

 unusual to be able to make an absolute diagnosis as to their 

 nature, but it may be done at times. Yet such an examination is 

 often useful. If suspicious bacilli are present you should inject 

 antitoxin forthwith ; if no suspicious bacilli are seen it is safe to 

 wait for the result of the cultural examination. Here the use of 

 Gram's stain (which need not necessarily be associated with a 

 counterstain) is most useful. If you are quite certain that your 

 material was taken from the affected area, and if you find no 

 stained bacilli in a fairly thick film, it is safe to withhold anti- 

 toxin pending developments, and vice versa. There are not many 

 Gram-positive bacilli other than those of diphtheria to be met 

 with in inflamed throats. 



Interpretation of Results. 



The discovery of the diphtheria bacillus in the exudate may mean — 



{a) That the patient is suffering from diphtheria. 



(J) That he has suffered from diphtheria and is now con- 

 valescent, but is still infectious. The bacilli may persist for weeks 

 or months, and while they do so the patient must be isolated and 

 treated with antiseptic gargles. In cases where the bacilli persist 

 in spite of treatment, it is not uncommon to find that the patient 

 suffers from adenoids or enlarged tonsils, and the organisms may 

 rapidly disappear if these are attended to. 



(c) That he is in danger of acquiring diphtheria if subjected 



