MENINGITIS DUE TO OTHER ORGANISMS 257 



of cases, especially in children, are due to the pneumococcus. In 

 many instances where no other lesions are present the extension 

 is by the Eustachian tube to the middle ear. In other cases the 

 path of infection is from some other lesion by means of the 

 blood stream. This organism also infects the meninges not 

 infrequently in lobar pneumonia, and in some 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. Sporadic 

 cases of meningitis occur associated with organisms which 

 resemble the influenza bacillus morphologically and also in 

 presenting hsemophilic culture reactions, but which possess 

 pathogenic properties for rabbits and guinea-pigs. Both in the 

 cerebro-spinal fluid and in cultures, these bacilli frequently show 

 a tendency to produce long filamentous forms and also may 

 show a beading of the protoplasm, which gives them a diph- 

 theroid appearance. The cases from which such bacilli have 

 been isolated have chiefly occurred in children, are extremely 

 fatal, and probably often follow on an otitis media, from which 

 condition similar organisms have been isolated. Sometimes the 

 meningitis is part of a septicsemic or pyaemic process, in the 

 latter the joints are often affected. It is impossible at present 

 to say whether the organisms associated with such conditions 

 are true influenza bacilli or are merely allied to them. They 

 certainly tend to be more widely distributed in the body of the 

 infected individual than is the case in the disease known clinically 

 as influenza. On the other hand, influenza appears under several 

 forms, and considerable variations may exist in the virulence 

 of strains responsible for different outbreaks. 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, 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 diplo- 

 coccus intracellularis. 



