20 



II.— TYPES OF PNEUMOCOCCI OBTAINED FROM CASES 

 OF LOBAR PNEUMONIA. 



By Fbed. Griffith, M.B. 



PAGE 



Introduction; ----------20 



Technique for differentiation of type ------ 21 



Isolation of pneumooocoi - - - - - - 21 



Preparation of pneumococcal agglutinating sera in rabbits 22 

 M i tliut I of performing agglutination test - - - 22 



Preparation and test of protective sera - - - - 24 



Uniformity of technique for the diagnosis of type - - - 25 



1 distribution of types in the present series of 150 cases - - 26 



Atypical strains and the question of their serological classification - 27 

 Suggestions for uniformity in classification - - - - 30 



Immunological inih'pi'ndence of the races of pneumococci - - 31 



Protection tests with Types I, II and III - - - 31 



Agglutination of Group IV strains - - - - 32 



Protection tests with Group IV- - - - -33 



Varieties of type yielded by the same patient - - - - 35 



Action of culture and pneumococcal exudates on immune serum - 38 



A I (sorption of protective substances - - - - - - 40 



Effect of intravenous inoculation of culture on the protective bodies 



and agglutinins in an immunised animal - - - - 43 



Disappearance of pneumococci in passively immune mice - - 44 



General conclusions -----...45 



Introduction. 



The study of types of pneumococci is important from two 

 aspects, the therapeutic and the epidemiological. In the first 

 place, almost all the available laboratory data show that the 

 action of antipneumococcal serum is directed almost solely against 

 pneumococci of the same type as that producing the serum. 

 The American experiments on monkeys are an important part 

 of this evidence and are supported by their observations on the 

 selective action of antipneumococcal serum in the treatment of 

 human pneumonia 



On the epidemiological side, the close scrutiny of the sero- 

 logical types occurring in different bacterial species, such as 

 the pneumococcus, meningococcus, etc., may some day provide 

 an explanation why a ubiquitous and apparently harmless 

 organism may suddenly become pathogenic for its host and of 

 such high infectivity as to propagate an epidemic. The im 

 portance of the subject has recently been emphasised by the 

 Health Committee of the League of Nations in their Conference 



