184 BACTERIOLOGY FOR NURSES 



Mixed Infections. The diphtheria bacillus is not the only 

 organism usually found in the false membrane. Associated with 

 it are frequently found the pyogenic cocci. The streptococcus 

 is an especially useful ally in disintegrating the surface cells of 

 the mucous membrane, and making possible the penetration of 

 the diphtheria bacillus into the deeper tissues, thus facilitating the 

 absorption of its toxin. Certain suppurative conditions of the 

 throat are unquestionably due to the pyogenic cocci. In most 

 cases of fatal broncho-pneumonia following diphtheria streptococci 

 or pneumococci or both are usually the inciting organisms and as 

 diphtheria antitoxin has absolutely no effect on them they fre- 

 quently are the cause of death. The presence of certain other 

 bacteria may often be detected by a difference in the exudate; 

 for example : B. fusiformis gives rise to an offensive odor, B. 

 pyocyaneus to a bluish green color. 



Bacteriological Diagnosis. A pseudomembrane in the nose 

 or throat is usually but not always the result of an infection by 

 the Loeffler bacillus. Many other organisms frequently present 

 in the throat secretions, such for example as streptococci and 

 pneumococci, can under certain conditions produce a local lesion 

 very similar to that of a mild case of diphtheria. Vincent's angina 

 and the pseudomembrane in scarlet fever somewhat resemble 

 that produced by the diphtheria bacillus. Generally, however, 

 the deposit in the first-named diseases appears rather as an exudate 

 than a membrane. 



Nearly all membranous affections of the nose are diphtheritic, 

 as are also thick, grayish membranes spreading over a large portion 

 of the tonsils and the soft palate. Seen on the tonsils alone the 

 presence of the diphtheria bacillus is less sure. 



In uncertain cases bacterial examination is of the greatest value 

 since the disease has such a rapid onset and the early adminis- 

 tration of antitoxin is necessary both for the suspected case and 

 those who may come in contact with it. 



The examination of cultures made from suspected throats is 

 usually a routine procedure in municipal laboratories. Outfits 

 are supplied to physicians on request. These consist as a rule 



