Bactericidal Action on Pneumococcus 223 



108 (2068) 



A method for demonstrating growth-inhibitory and bactericidal 

 action on the pneumococcus of a normal serum- 

 leucocyte mixture. 



By O. H. ROBERTSON and RICHARD H. P. SIA. 



[From the Department of Medicine, Peking Union Medical 

 College, Peking, China.] 



I 



Methods heretofore employed in testing for growth inhibiting 

 and bactericidal action of the blood on pneumococcus have con- 

 sisted in suspending small numbers of pneumococci in whole 

 blood, serum or serum-leucocyte mixtures, contained in the capil- 

 lary pipette, test tube or hanging drop. Results of tests on serum 

 and serum-leucocyte mixtures have shown a general agreement 

 that neither serum nor serum and leucocytes together inhibit the 

 growth of the pneumococcus. Studies on whole blood, however, 

 have resulted in most divergent findings. Certain workers 

 (Wright, Heist and Solis Cohen) report the finding not only of 

 growth inhibition, but also of pneumococci dal activity in the 

 blood of animals resistant to pneumococcus infection. Other in- 

 vestigators, (Barber, Bull and Bartual) using the same methods 

 on the blood of the same and other, resistant animal species failed 

 to find anything more than growth retardation. A review of the 

 more important literature on this subject leads one to the con- 

 clusion that with the methods heretofore employed it is not pos- 

 sible to demonstrate with any degree of constancy either growth 

 inhibitory or bactericidal activity of the normal blood for the 

 pneumococcus. 



It seemed probable to the writers that further information on 

 this subject could be obtained were it possible to work out a 

 method that should incorporate certain conditions under which 

 inhibition of growth with subsequent destruction of the pneu- 

 mococcus might be expected to occur in the body. In the tissues 

 of the animal body fluid currents operate to bring the leucocytes 

 and implanted micro-organisms into intimate contact. In the 

 capillary pipette or test tube this constant mixing process is ab- 

 sent. Growth inhibition and bacteriolysis probably occur only if 



