THE BACILLUS AND THE BACTERIOLOGY OF DIPHTHERIA 217 



without leaving a bleeding surface, at least until convalescence. The 

 tissues surrounding the exudate are more or less inflamed and swollen. 

 Where other bacteria produce the irritant the exudate, except in cases 

 due to the bacillus described by Vincent, is usually loosely attached, 

 collected in small masses, and easily removable. Exceptions, how- 

 ever, occur in both these diseases, so that in true diphtheria the exudate 

 may be easily removed, and in lesions due to other bacteria the exudate 

 may be firmly adherent. 



Paralysis following a pseudomembranous inflammation is an almost 

 positive indication that the case was one of diphtheria, although slight 

 paralysis has followed in a very few cases in which careful cultures 

 revealed no diphtheria bacilli. These, if not true diphtheria, must be 

 considered very exceptional cases. 



Bacteriological Diagnosis. From the above it is apparent that fully 

 developed characteristic cases of diphtheria are readily diagnosticated, 

 but that many of the less marked, or at an early period undeveloped, 

 cases are difficult to differentiate the one from the other. In these 

 cases cultures are of the utmost value, since they enable us to isolate 

 those in which the bacilli are found, and to give preventive infections 

 of antitoxin to both the sick and those in contact with them, if this has 

 not already been done. As a rule, cultures do not give us as much 

 information as to the gravity of the case as the clinical appearances, 

 for by the end of twenty-four to forty-eight hours the extent of the 

 disease is usually possible of determination. The reported absence 

 of bacilli in a culture must be given weight in proportion to the skill 

 with which the culture was made, the suitableness of the media, the 

 location of the disease, and the knowledge and experience of the one 

 who examined it. 



Diphtheria does not occur without the presence of the diphtheria 

 bacilli; but there have been many cases of diphtheria in which, for one 

 or another reason, no bacilli were found in the cultures by the examiner. 

 In many of these cases later cultures revealed them. In a convalescent 

 case the absence of bacilli in any one culture indicates that there are 

 certainly not many bacilli left in the throat. Only repeated cultures 

 can prove their total absence. 



TECHNIQUE OF THE BACTERIOLOGICAL DIAGNOSIS. Collection of 

 the Blood Serum and its Preparation for Use in Cultures. A covered 

 glass jar, which has been thoroughly cleansed with hot water, is taken 

 to the slaughter-house and filled with freshly shed blood from a calf or 

 sheep. The blood is received directly in the jar as it spurts from the 

 cut in the throat of the animal. After the edge of the jar has been 

 wiped it is covered with the lid and set aside, where it may stand quietly 

 until the blood has thoroughly clotted. The jar is then carried to the 

 laboratory and placed in an ice-chest. If the jar containing the blood 

 is carried about before the latter has clotted, very imperfect separation 

 of the serum will take place. It is well to inspect the blood in the jar 

 after it has been standing a few hours, and, if the clot is found adhering 

 to the sides, to separate it by a rod. The blood is allowed to remain 



