216 BACTERIOLOGY OF THE EYE 



Microeoccus Catarrhalis (Pfeiffer). 



According to our present knowledge, the organisms mentioned are to 

 be considered as belonging to the group of the Microeoccus catarrhalis 

 of Pfeiffer, the Gram-negative Diplococci resembling the Gonococci, 

 which commonly inhabit the nose and throat, and which are met with 

 in catarrhal secretions from these membranes, as well as in bronchitis. 1 

 According to the researches of Ghon and H. Pfeiffer, Czaplewski and 

 Urbahn, von Lingelsheim and Brons, the Microeoccus catarrlialis is 

 the most vigorous and most resistant of the three members of the 

 family of Gram-negative Diplococci (Gonococcus, Meningococcus, ]\Ii<-r<>- 

 coccus catarrhalis). 



It is generally larger than the Gonococcus (cf. Plate II., Fig. III.), 

 but the difference is not always obvious the more so as these bacilli, 

 especially in the secretions of the nose or of cases of bronchitis, often 

 lie in the cells. The cocci sometimes occur in large numbers in the 

 conjunctival secretion, even when there is only a very slight irritation. 

 Where the cocci do lie in the cells these are not so fully packed with 

 them as is the case with the Gonococci. 



The Microeoccus has a strong tendency to develop large forms when in culture ; 

 tetrads commonly occur. Old cultures show plump degeneration forms. Decolor- 

 ization with Gram is quite regular, and as rapid as is the case with the Gonococcus. 

 In contradistinction to the Gonococcus, the cultures show colonies of a more 

 greyish-white colour (having a consistence somewhat like mortar, with a centre 

 which is slightly yellowish, becoming later brownish). According to Brons, the 

 colonies are very easily moved about as a coherent mass without being especially 

 tough in consistence. The margins of the larger colonies appear indented and 

 slightly raised. Under low magnification the colonies appear coarsely granular. 

 Growth is free on all media, even at temperatures under 20 C. In gelatine stab the 

 growth takes place only in the upper part in the form of a small bead, with no 

 liquefaction, and a grey mass radiating outwards on the surface. Stroke cultures 

 on agar, serum agar, and sugar agar form a greyish-yellow bright streak, with a 

 raised border. In bouillon a flocculent deposit forms at the bottom and on the 

 walls of the tube. If the bouillon is very still, then the fluid may remain clear, 

 and a fine surface scum or a ring may form (Brons). In milk good growth 

 without coagulation. 



Neutral red litmus whey after a few days becomes blue (alkaline). Following 

 Lingelsheim and His, Brons tested the power of fermenting the various sugars. 2 

 Micrococcus catarrhalis did not ferment any of them. There was no formation 

 of indol. 



They are more resistant than the Gonococcus against the influence of cold 

 and heat. 



1 From its resemblance to the Meninyococci found in cerebro-spinal meningitis (vide infra), 

 many authors have come to the conclusion that the Meningococcus is commonly found in 

 the nose under normal circumstances. 



2 Regarding this differential diagnosis, cf. the experiments of Dunn and Gordon 

 (B. M. J., 1905, ii. 421). 



