DIFFERENTIATION OF THE OONOCOCCUS FROM THE MENINGOCOCCUS 551 



not emulsify so readily ; colonies of the meningococcus, on the other hand, are 

 butyrous and emulsify with the greatest of ease. Biochemically, the menin- 

 gococcus produces acid in glucose and maltose, the gonococcus in glucose only ; 

 as pointed out on page 534 a medium containing human or rabbit serum should 

 be used for testing the fermentation of maltose. The agglutination test is only 

 of limited value, since there exists a group relationship between the two organisms 

 (Bruckner and Cristeanu 19066, Wollstein 1907, Elser and Huntoon 1909, Gordon, 

 M. H., 1925). The meningococcus is more toxic to animals ; tested by intra- 

 peritoneal injection on mice or guinea-pigs a smaller dose of meningococci than 

 of gonococci is required, whether alive or dead, to cause death. 



N. catarrhalis. — This organism has been variously described by different workers. 

 Ghon and Pfeiffer (1902), who first studied it fully, stated that in sputum 

 it occurred in pairs, tetrads, or occasionally small groups ; the organisms were 

 shaped like cof5ee-beans, and were both intra- and extra-cellular. In culture 

 they appeared larger, were generally in tetrads, and stained evenly. On agar 

 after 24 hours, the colonies resembled in size those of Streptococcus pyogenes ; 

 they were convex, whitish-grey, with a glistening surface and an eaten edge. 

 After 3 or 4 days they were 3 to 4 mm. in diameter, and were differentiated into 

 a prominent, more elevated, opaque, slightly brownish centre, and a thinner, grey, 

 transparent, wave-like periphery with a crenated edge ; the consistency was 

 friable, and in saline they auto-agglutinated. A more or less similar description 

 was given by von Lingelsheim (1906) ; he stated that the colony was smaller 

 than that of a meningococcus colony, and that even on ascitic agar the dia- 

 meter never exceeded 1-2 mm. Elser and Huntoon (1909) described two types of 

 colony, one resembling Ghon and Pfeiffer's description, the other like a small 

 meningococcus colony. J. E. Gordon (1921) described four types of colony : (1) 

 like Ghon and Pfeiffer's ; (2) similar to the first, but coloured pale yellow ; (3) 

 small, flat, grey, translucent, amorphous colonies with a smooth ghstening surface 

 and entire edge ; (4) almost pin-point, transparent glistening colonies with a 

 smoothly rounded edge ; morphologically, these consisted of giant cocci showing 

 metachromatic staining. It seems clear that the colonial appearance of N. catar- 

 rhalis is subject to variation ; in all probability both smooth and rough types are 

 formed, similar to those of the meningococcus and the gonococcus. In gelatin 

 stab culture there is a poor growth confined to the upper part of the tube ; there 

 is no liquefaction. There is no turbidity in broth, but a granular deposit is formed ; 

 if the tube is kept still, a surface membrane may appear. Growth occurs within 

 a range of 18° to 42° C, the optimum being at 37° C. There is no development 

 under anaerobic conditions. Growth is favoured by blood, serum, and ascitic 

 fluid, but not by glycerine. The organism appears to be more resistant than the 

 meningococcus or gonococcus ; cultures are said to live for 4 or 5 months at 

 21° C, if prevented from drying ; the organisms may live in dried sputum for 27 

 days ; they are killed by heating to 65° C. for 30 minutes. No sugars are fer- 

 mented. The virulence ot this organism to laboratory animals is low. The 

 rabbit is resistant, but guinea-pigs injected intraperitoneally with large doses — 

 half to one agar slope — die of toxaemia in about 24 hours. At post mortem there 

 is a mild degree of peritonitis, slight enlargement of the spleen, and hypersemia 

 and degeneration of the viscera ; the organisms may be recovered from the peri- 

 toneal exudate, but rarely from the heart's blood. Heat-killed cultures are almost 

 as fatal as living ones. 



