208 



BACTEKIOLOGY OF THE EYE 



have never found the Streptococcus growing at the same time. The same is true 

 of the numerous cases of pneumococcal conjunctivitis. Such findings as I have 

 figured are rightly to be considered as pure infections with Pneumococcus ; or, at 

 least, we must attribute to the Pneumococcus the causation of the diseased process. 

 When Pneumococci do form chains in the secretion, they are quite short, straight 

 little ones, consisting of two or three members, which are to some extent elongated 

 and vary in thickness ; while the streptococcal chains are formed of rounded or 

 flattened cocci, of which the adjoining pairs often lie closer, and fuse into a Diplo- 

 coccus. The diagnosis of Pneumococcus in secretion can only be difficult as against 

 the Streptococcus mucosus. In preparations of the secretion of our case (Rupprecht) 

 elongated Diplococci were also found, although in the culture only Streptococcus 

 mucosus grew. This variety of the Streptococcus is so closely related to the 

 Pneumococcus that it can be considered as a variety of that organism (cf. p. 187). 



The Streptococcus and the Pneumococcus belong to the great group of the 

 chain- formers. Kruse and Passini have named the Pneumococcus the 'Strepto- 

 coccus of the mucous membranes,' so that the detailed differential diagnosis may 



appear to many to be unnecessary at 

 a time when the natural relationships 

 in bacteriology are always being given 

 more weight. This differential diag- 

 nosis, however, alone determines the 

 possibility of our evolving a specific 

 serum treatment for the two organisms, 

 and even though this has not yet 

 achieved any definite success, it still 

 deserves our full consideration, and 

 the ophthalmic surgeon should be 



*A *j+'l!,\ ^1 familiar with the exact differential 



- ' Fi&w 4^ xLM diagnosis between Pneumococcus and 



Streptococcus. If we have only cul- 

 tures to test, the diagnosis is more 

 difficult; still, it can be made on the 

 following grounds : 



(a) The presence of elongated Diplo- 

 cocci or cocco-bacillary forms on agar 

 and serum. 



(6) The growth of many Strepto- 

 cocci on gelatine. 



(c) The addition of 1 to 3 per cent, of taurocholate of soda (Neufeld) to the media 

 prevents the growth of Pneumococcus, but not that of Streptococcus pgogenes. 

 The salt can also be dropped into bouillon. Pneumococcus then dissolves after a 

 short time in the incubator, and the fluid clears. Streptococcus bouillon remains 

 unchanged. 



(d) By inoculation in the blood of a white mouse, the Pneumococci are to be 

 found in their typical capsulated forms. 



(The so-called Streptococcus mucosus in these tests usually behaves as a 

 Pneumdcoccnt.) 



(Though the Streptococci in other parts of the body are such common pathogenic 

 agents, in the eye they are seldom in question. Their occurrence on the normal 

 and diseased conjunctiva is described on pp. 41, 205. 



They seldom cause corneal infection. They are relatively rare in simple catarrhal 

 or purulent dacryocystitis ; * they are more commonly found in the pus of a 



1 The Pneumococci which form chains in culture are here excepted. 



FIG. 44. DRAWN FROM THE SECRETION 

 IN A FRANKEL'S CASE. 



