248 EPIDEMIC CEREBRO-SPINAL MENINGITIS 



cases with head symptoms we have found it present where there 

 was merely a condition of congestion. The pneumobacillus also- 

 has been found in a few cases. Meningitis is not infrequently 

 produced by streptococci, especially when middle-ear disease is 

 present, less frequently by one of the staphylococci ; occasionally 

 more than ; one organism may be concerned. In meningitis 

 following influenza the influenza bacillus has been found in a 

 few instances, but sometimes the pneumococcus is the causal 

 agent. Cases of meningitis occur associated with organisms 

 which resemble the influenza bacillus morphologically and also 

 in presenting haemophilic culture reactions, but which possess 

 pathogenic properties for rabbits and guinea-pigs. These bacilli 

 frequently both in the cerebro-spinal fluid and in cultures show 

 a tendency to produce long filamentous forms and also under 

 both circumstances may show a beading of the protoplasm 

 which gives them a diphtheroid appearance. Gram-negative 

 anaerobic bacilli have also been found in cases of meningitis. 

 An invasion of the meninges by the anthrax bacillus occurs, 

 but is a rare condition ; it is attended by diffuse 

 haemorrhage in the subarachnoid space. In tubercular 

 meningitis the tubercle bacillus, of course, is present, especially 

 in the nodules along the sheaths of the vessels. 



In conclusion, here it may be stated that mixed infections 

 may occur in meningitis. Thus the pneumococcus has been 

 found associated with the tubercle bacillus and also with the 

 diplococcus intracellularis. 



Methods of Examination. During life these involve the microscopic 

 investigation of the centrifuged lumbar puncture fluid and making 

 cultures therefrom. For the former, Gram-stained smears make the 

 recognition of the meningococcus relatively easy, and the presence of 

 Gram-negative cocci, especially within cells, is practically diagnostic of 

 a case of cerebro-spinal fever. Tubes of serum-agar, nasgar (pp. 42, 43), 

 or agar containing 25 per cent, of ascitic or ovarian fluid, may then be 

 inoculated. The difficult cases are those where no bacteria can be found 

 microscopically in the lumbar fluid. Here the character of the exudate 

 may give help. A predominance of polymorphonuclear cells is usually 

 manifest in meningococcic, pneumococcic, and influenzal cases, whereas in 

 tubercular meningitis the exudate is chiefly lymphocytic. In such 

 circumstances, besides other media, a tube of blood-smeared agar should 

 be inoculated in case the pneumococcus or the influenza bacillus is the 

 causal organism. To speak generally, if with a polymorphonuclear exu- 

 date no growth occurs in the media mentioned the case is most likely to be 

 due to the meningococcus. In tubercular cases it is sometimes impossible 

 to demonstrate the bacilli microscopically in the exudate, though on 

 careful search they may often be found. 



