OCCURRENCE OF CAUSATIVE AGENTS. 135 



Pneumococcus-angina, further, pursues frequently the char- 

 acteristic course outlined, though by no means always. 

 It is to be added that isolated cases of tonsillitis have been 

 reported in which the bacterium coli commune exclusively 

 has been found. 



Above all, however, in a not inconsiderable number of 

 cases of angina, there is mixed infection with several of the 

 micrococci named. Then, most commonly the two varieties 

 of bacteria are found together from the beginning. At 

 times, however, only streptococci can be demonstrated at 

 first, and after some days also staphylococci, or even the 

 latter alone. Under these conditions it must be concluded 

 that the one coccus has associated itself with or overgrown 

 the other. The frequency of these mixed infections, which 

 clinically are indistinguishable from the pure infection, alone 

 renders impossible a rigid separation of the anginas accord- 

 ing to their causative agents. 



Scarlatinal angina is usually associated with the presence 

 of streptococci. 



The bacteriologic diagnosis can, according to what has 

 been said, be made only with a certain degree of probability 

 from the clinical picture and the course of the disease. A 

 positive diagnosis is possible only on microscopic and cul- 

 tural investigation. The latter is made simply by rubbing 

 a sterile swab of cotton that has been applied to the tonsil, 

 or a bit of secretion or membrane obtained by means of 

 a sterilized platinum loop, upon from three to five glycerin- 

 agar tubes, or, better in the differential diagnosis of diph- 

 theria upon from three to five tubes of LofHer's serum, or 

 upon a serum-plate. The bacterial decision will frequently 

 be questionable on account of the impossibility of exclud- 

 ing diphtheria with certainty by other means. Detailed 

 reference will be made to this point in the section on 

 Diphtheria. 



From what has been said, it will be clear that the dem- 

 onstration of staphylococci, streptococci, or pneumococci, is 

 available for purposes of prognosis only with great caution. 



OTITIS MEDIA. 



In cases of serous inflammation of the middle ear, as 

 well as in cases of suppurative or hemorrhagic type, there 

 have been found the diplococcus pneumoniae Frankel, the 



