650 THE MENINGOCOCCUS 



Gonococcus and Meningococcus is further confirmed by the fact that antigono- 

 coccal serum contains no immune body (sensibilisatrice) for the Meningococcus and 

 conversely (Vannod). 



The agglutination reaction. For the diagnosis of the Meningococcus the 

 agglutination reaction should be carried out as follows : 



1. Take five narrow sterile test-tubes. 



2. To the first add 1 c.c. of a 1 in 100 dilution of unheated antimeningococcal 

 serum. To the second 1 c.c. of a 1 in 200 dilution of the same serum. To 

 the third 1 c.c. of a 1 in 100 dilution of normal horse serum. To the fourth 

 1 c.c. of a 1 in 200 dilution of normal horse serum. To the fifth 1 c.c. of 

 normal saline solution. 



3. To each tube add one loopful of a young agar culture of the orgasnism 

 under investigation. 



4. Incubate the tubes at 37 C. for 24 hours. (If no agglutination has 

 taken place repeat the experiment and incubate at 55 C.) 



5. If the organism be a Meningococcus, on taking the tubes out of the 

 incubator there will be very distinct agglutination in tubes Nos. 1 and 2 while 

 the emulsion in the other three tubes will be cloudy. 



SECTION IV. THE ISOLATION AND IDENTIFICATION OF THE 

 MENINGOCOCCUS. 



1. The diagnosis of meningococcal meningitis. The diagnosis of meningo- 

 coccal meningitis should be based upon the following characteristics of the 

 organism isolated. 



1. Microscopical appearance : " coffee bean " diplococci situated, in the 

 case of meningeal exudates, within the leucocytes. 



2. Staining reactions : gram-negative. 



3. Cultural characteristics : capacity to grow on ordinary agar : fermenta- 

 tion of glucose and maltose, no action on Isevulose and saccharose. 



4. Agglutination by a specific serum. 



2. The isolation of the organism. The cerebro-spinal fluid and also the 

 exudate on the naso-pharynx should be examined. 



A. Cerebro-spinal fluid. To establish a diagnosis of meningococcal 

 meningitis it is essential to examine the fluid obtained by lumbar puncture. 



In cases of this disease the cerebro-spinal fluid is generally purulent or cloudy : 

 but this indication, though present according to Netter in 96 per cent, of cases, is 

 not pathognomonic. In the early stages of the infection (during the first 24 hours) 

 the cerebro-spinal fluid is clear and it may again become clear later, towards the end 

 of the second week. 



Centrifuge the cerebro-spinal fluid in a sterile tube and then proceed as 

 follows : 



1. Examine a portion of the deposit microscopically. Stain a film with a 

 simple stain and another by Gram's method. 



2. Sow the remainder of the deposit on blood-agar or ascitic-agar and 

 incubate for 24 hours at 37 C. Examine the colonies and sow some on 

 glucose and on maltose tinted with litmus or neutral red (vide ante] and use 

 others for the agglutination reaction. 



Vincent and Bellot's reaction. Centrifuge the cerebro-spinal fluid immedi- 

 ately after collection. Drop 50-100 drops of the clsar supernatant fluid into 

 each of two sterile tubes : to one tube add 1 or 2 drops of antimeningococcal 

 serum and incubate for 6-12 hours at 37 C. or 55 C. If the case be one 

 of meningococcal meningitis the tube to which the antimeningococcal serum 

 has been added is slightly cloudy while the control tube remains clear. 



