BLOOD CULTURES AND BLOOD PARASITES 413 



tubes instead of inoculating the bouillon tubes. Contamination with staphylococci 

 or the presence of staphylococci, streptococci, or plague bacilli in septicsemic con- 

 ditions show easily accessible colonies. 



Schotmuller adds i to 3 c.c. of blood to liquefied agar at 45C., and after mixing 

 pours into plates. The standard method formerly was to add the blood to an 

 excess of bouillon (i to 5 c.c. of blood to 100 c.c. or more of bouillon). 



The method of culturing blood we now follow in our laboratory is 

 the following: 



A stout hypodermic needle is attached to about 6 inches of rubber tubing which in 

 turn is pushed over a downward bent glass tube which passes through a doubly 

 perforated rubber stopper. A second glass tube, which also passes through the stop- 

 per, is bent upward to be attached to a second piece of rubber tubing for use in suc- 

 tion by the mouth. The glass tubes project about Y^ inch below the undersurface 

 of the rubber stopper and above are about 2% inches including the bent arm. This 

 system of tubing and stopper is readily sterilized by boiling in a pan or instrument 

 sterilizer. As a receptacle for the blood we employ Erlenmeyer flasks of 100 c.c. 

 capacity, containing 10 to 25 c.c. of salt solution with i or 2% of sodium citrate, for 

 prevention of coagulation. These citrated salt solution flasks are plugged with cot- 

 ton, sterilized and kept on hand ready for immediate use, so that we only have to 

 sterilize the stopper and tubing by boiling and flame the neck of the flask when re- 

 moving the cotton plug to insert the stopper of the system. By suction we can take 

 any amount of blood desired. I usually count the drops of blood as they fall into 

 the citrated salt solution allowing 16 drops to the cubic centimeter. In this way we 

 may take from 10 to 25 c.c. of blood at the bedside and then later on in the laboratory, 

 when it is convenient, inoculate various media from the flask. For plates add 2 or 3 

 c.c. of this citrated blood to 6 or 8 c.c. of melted agar at 45C. The blood mixture 

 can also be added to various sugar bouillons for fermentation reaction. Finally we 

 place the receiving flask in the incubator and culture it as well as the other media. 



Of course in inoculating the various plating or sugar tubes from the flask there is 

 some liability to contamination. This may be avoided by removing with a sterile 

 pipette 10 to 20 c.c. from the flask containing the citrated blood to carry out the 

 inoculations instead of pouring out directly from the flask. 



A very useful procedure in the isolation of streptococci, pneumo- 

 cocci, plague and anthrax bacilli is to inject i to 2 c.c. of blood into 

 suitable animals. When infecting mice use only about 0.2 c.c. sub- 

 cutaneously at root of tail or, more certain of results, the injection of 

 about i c.c. of the blood intraperitoneally. Streptococci, even from 

 virulent human infections, are uncertain in their action on animals 

 so that the failure to produce septicaemia in the mouse does not neces- 

 sarily indicate that the organism is of slight virulence. 



By using the bile media, we can take the blood from the ear in typhoid cases, 

 if preferred. Then if chance staphylococcic contamination occurs, such colonies 

 are readily differentiated from typhoid ones by the pink color on lactose litmus 



