54 BACTERIOLOGICAL DIAGNOSIS. 



patient must be isolated and treated with antiseptic 

 gargles. 



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

 subjected to any influence which lowers his vitality, or 

 which would cause ordinary sore throat in any ordinary 

 person. 



(d). It always means that the person may communi- 

 cate diphtheria to a susceptible subject. 



The significance of Hoffman's bacillus is not yet 

 settled. It is frequently found in the throat when the 

 patient is convalescing from an attack of diphtheria, 

 and sometimes in subjects who afterwards develop 

 diphtheria. It also appears to cause epidemics of sore 

 throat which do not present anything remarkable in 

 their clinical characters. It is safest to regard any 

 patient who presents these bacilli as being infectious. 

 In other words, in the present state of our knowledge it 

 is best not to draw any distinction between Hoffman's 

 bacillus and the true diphtheria bacillus, as far as infec- 

 tivity is concerned. 



A negative result may mean : 



(a). That the patient is not suffering from diphtheria. 



(b). That the swab did not touch the affected area. 



We exclude errors in technique and observation. 



A sterile culture may mean : 



(a). That an antiseptic was used too soon before 

 taking the swab. 



(b). That the diseased portion of the throat was not 

 touched. Other parts of the t mouth contain numerous 

 bacteria, but many of them do not grow well on blood 

 serum or ascitic agar. 



We again exclude errors arising in the laboratory. 



Whenever the culture tube remains sterile the exam- 

 ination should be repeated. 



