168 DIPHTHERIA 



During the sixties of the past century, many were busy searching 

 for the particulate cause of this disease and several organisms were 

 presented as claimants for this honor, but at that time bacteriologic 

 methods had not been sufficiently developed to enable the most expert 

 to pick out the one responsible for the disease. In 1883 Klebs called 

 attention to a bacillus with well-marked characteristics, frequently 

 found in diphtheritic throats, and a year later Loffler continued this 

 work. 



The Bacillus. The Klebs-Loffler bacillus is a non-motile rod, 

 generally straight, but sometimes slightly bent. Its length is quite 

 variable (from 3 to 5 microns) and its breadth almost one-fourth its 

 length. The most characteristic form of the bacillus is the club shape. 

 All the rods do not have this form, but in every field there are many 

 so characteristically clubbed that the expert has no difficulty in identi- 

 fication at sight. This is true especially of cultures made directly 

 from the throat. Even the presence of other bacteria does not prevent 

 identification. A sterilized cotton swab is drawn over the membrane 

 in the throat and then over the surface of a slant serum tube. After 

 from six to twelve hours in the incubator, a stain is made from the 

 growth on the serum. While the diphtheria bacillus takes most basic 

 stains well, Loffler's alkaline methylene blue is most generally employed. 

 Direct microscopic examination of this stain enables the expert to 

 determine with certainty in the great majority of instances the presence 

 or absence of the specific organism and announce the bacteriologic 

 diagnosis. The bacteriologist does not depend solely on the presence 

 of club-shaped bacilli. The Klebs-LorHer bacillus has a peculiar seg- 

 mented appearance when colored with the stain mentioned above. 

 This is more easily recognized than described, but it becomes so 

 familiar to one engaged in this work that he is seldom mistaken. The 

 morphologic identification is rendered more easy by the fact that as a 

 rule the only other bacteria on the slide are streptococci. If the observer 

 satisfies himself that only streptococci are present, he makes a negative 

 report. In a few instances, there are diphtheria-like organisms which 

 may leave one in doubt. However, when in doubt the only wise thing 

 to do is to make a positive diagnosis, when the case will be properly 

 isolated and treated with antitoxin. 



