EPIDEMIC CEREBRO-SPINAL MENINGITIS 213 



EPIDEMIC CEKEBE.O-SPINAL MENINGITIS. 



As the result of observations on this disease in different parts 

 of the world, it has been now established that the causal agent 

 is the dijdococcns intracdlidaris meningitidis first described by 

 WeicTiselbaum. This organism is a small coccus measuring 

 about 1 /x in diameter and usually occurs in pairs, the adjacent 

 sides being somewhat flattened against each other. In most 

 cases the cocci are chiefly contained within polymorphonuclear 

 leucocytes in the exudation (Fig. 72) ; in some cases, however, 

 the majority may be 

 lying free. It stains 

 readily with basic aniline 

 dyes, but loses the stain 



Gram's metJtmcL tne 



readiness with which the 

 organism decolorises 

 varying with different 

 strains. Both in appear- 

 ance and in its staining 

 reactions it is superfici- 

 ally similar to the gono- 

 coccus (vide infra). The 

 organism can readily be 

 cultivated outside the 

 body, but the conditions 

 of growth are somewhat 

 restricted agar with an 

 admixture of serum or 

 blood (preferably human) 

 is most suitable. 1 Strains 



separated in different epidemics appear to present slight in- 

 dividual variations, but the following description may be taken 

 as summing up the common characters. Growth takes place 

 best at the temperature of the body, and practically ceases 

 at 25 C. On serum agar the colonies are circular discs of 

 almost transparent appearance and possessing a smooth shining 

 surface ; they have little tendency to become confluent. When 

 examined under a low magnification the colour is seen to be 

 somewhat yellowish and the margins usually are smooth and 



1 A very good medium is one composed of 1 part of ascitic fluid and 6 

 parts of 1 per cent glucose agar ; the serum obtained aseptically^is added to 

 the agar in the melted state at 45 C. and the tubes are tested as regards 

 sterility by incxibation. 



Fia. 72. Film preparation of exudation from 

 a case of meningitis, showing the diplococci 

 within leucocytes. 

 Stained with carbol-thionin-blue. x 1000. 



