PNEUMOCOCCUS INFECTIONS IN MAN 461 



exercise care in this respect has lead to many Type IV reports 

 when the pneumonia was actually caused by I, II, or III. The 

 special sputum for typing -should be collected in a separate cup, 

 and not in the general sputum cup into which the patient has been 

 spitting all day. The patient should rinse his mouth thoroughly 

 with salt solution, bicarbonate of soda solution, or perhaps weak 

 alcohol, and a specimen of sputum should be immediately obtained 

 by coughing. It is collected in a sterile Petri dish or clean cup, 

 and should not be allowed to stand around in the ward for any 

 length of time, but should be sent to the laboratory, or stored in 

 the ice chest. 



A Gram stain should be made of the sputum as a preliminary 

 survey. A capsule stain may also be made with advantage. 



In the rare cases in which mice are not available, the sputum 

 should be plated upon blood agar plates for subsequent agglutination 

 or single colonies by the microscopic method. But this is not de- 

 sirable, and mice can usually be procured. We have found gray 

 mice quite as suitable as white mice, and in outlying laboratories 

 an extensive use of mouse traps will solve the problem. 



As soon as the sputum has been received in the laboratory it 

 should be washed. A small bit of sputum, preferably from the 

 center of a clump, is lifted with a platinum needle into three or 

 four Petri dishes containing sterile salt solution or broth, and gently 

 swabbed about. The thorough washing is extremely important for 

 clean-cut results. Some times the sputum can be directly sucked 

 up into a sterile syringe. If this cannot be done, it should be ground 

 in a sterile mortar with about 1 to 2 c.c. of sterile broth or salt 

 solution added gradually. About 0.5 c.c. of this is intraperitoneally 

 injected into a mouse. Great care should be exercised not to inject 

 too much since massive inoculation may give contaminating organ- 

 isms a chance, and many mice have been wasted in this way. In 

 the mouse the pneumococcus, if virulent, outgrows most other or^ 

 ganisms. However, occasionally mice will die of streptococcus 

 infection and may show streptococcus, influenza and occasionally 

 staphylococcus infection, but this is relatively infrequent. 



The mouse will appear very sick or die between ten and twenty- 

 four hours. When the mouse is either in extremis or dead it should 

 be immediately autopsied. 



Pin the mouse down on a small board, carefully dissect off the 

 skin and, with sterile instruments, open the peritoneum. 



