MICROCOCCUS CATARRHALIS 651 



The reaction sometimes fails ; and occasionally both tubes are cloudy 

 when it is of course valueless. But in general it is a useful test especially 

 when meningococci are not found in the cerebro-spinal fluid. 



Note. In a certain number of cases (25 per cent, according to von Lingels- 

 heim) no organism can be detected in the cerebro-spinal fluid though they 

 can be proved to be cases of meningococcal meningitis by examining the 

 agglutinating properties of the blood and by Vincent and Bellot's reaction : 

 and it must be assumed either that the organism was present in the early 

 stages of the disease and has vanished or that it is confined to the upper 

 part of the cerebro-spinal axis. 



B. Naso-pharyngeal exudates. The material must be collected from the 

 naso-pharynx from behind the fold of the palate. A small plug of sterile 

 wool fixed on a rigid metal wire and slightly curved at the end may be used 

 to collect the exudate : pass this wool plug as high as possible behind the 

 palate and sow the material without delay on ascitic-agar plates. Incubate 

 for 24 hours at 37 C. and carefully examine the colonies : any that look 

 suspicious must be tested as described above. Confusion is most likely to 

 arise with the Micrococcus catarrhalis (vide infra) ; this organism however 

 grows easily on all the ordinary media and does not ferment either glucose 

 or maltose. 



Micrococcus catarrhalis. 



In recent years German writers have described the occurrence in some respiratory 

 affections of a gram-negative organism morphologically similar to the Gonococcus 

 and which they designate the Micrococcus catarrhalis (Ghon, Pfeiffer, Bezan9on, 

 Israel and de Jong). 



This organism is frequently found in man in cases of bronchitis and pneumonia, 

 and in the sputum of tuberculous persons whose temperature is raised. Some 

 writers have confused the Micrococcus catarrhalis with the Meningococcus, / but it 

 is easily differentiated from the latter by its cultural characteristics. 



The Micrococcus catarrhalis grows well on ordinary media : does not ferment 

 carbohydrates : and is not agglutinated by an antimeningococcal serum. 



Experimental inoculation. The Micrococcus catarrMlis is only slightly virulent 

 for laboratory animals. It gives rise to small lesions of the pleura when inoculated 

 in very large doses into the pleural cavities of guinea-pigs or mice : rabbits are not 

 susceptible. 



Microscopical appearance. In sputum the organism is seen as irregular diplococci, 

 looking like coffee beans placed in pairs with their flattened surfaces adjacent. 

 They may be seen singly or in small groups, either free or within the leucocytes. 

 In cultures the appearance is much the same. The diplococci are sometimes arranged 

 in tetrads but more frequently in small clumps. Chains are never seen and the 

 organism is not surrounded by a capsule. 



The Micrococcus catarrhalis is easily stained by the basic aniline dyes and is 

 gram-negative. 



Cultural characteristics. The organism is aerobic and grows at 20 C. but the 

 optimum temperature is 37 C. 



Gelatin. A slow and scanty growth takes place at 20 C. The medium is not 

 liquefied. 



Broth. In broth at 37 C. a slight cloudiness and powdery deposit is formed. 



A gar. After 24 hours' incubation at 37 C. the growth consists of small, white, 

 irregularly rounded colonies. Later the centre becomes prominent and slightly 

 brownish in colour while the margins are wavy and jagged. 



Liquid rabbit serum. The growth is minimal on this medium and the organism 

 is not capsulated. 



M ilk. The medium is not coagulated as the result of the growth of the organism. 



Carbohydrate media. No fermentation. 



