CHAPTER XXVIII. 

 BLOOD CULTURES AND BLOOD PARASITES. 



CLINICALLY, the most important examination of the blood for para- 

 sites is for the presence of various bacterial infections and for certain 

 blood protozoa and also nlarial embryos. 



The modern method of culturing blood, especially for the detection 

 of typhoid or paratyphoid bacilli, is by the use of the- bile media of 

 Conradi. Test-tubes are filled with 7 to 10 c.c. of i% peptone ox bile, 

 or ox bile alone, and the medium is sterilized in the autoclave. It is 

 good practice to place the syringe in a plugged test-tube containing 

 salt solution, with the needle unscrewed. After autoclaving, the 

 sterile syringe can be taken to the bedside in the test-tube. Using a 

 wide test-tube, a forceps can be sterilized at the same time and used to 

 attach the needle to the barrel of the syringe. 



The skin should be scrubbed gently with green-soap solution and 

 water for about three minutes. The skin of the area to be punctured 

 should then be sterilized by the gentle application of Harrington's 

 solution (riot scrubbed) for one-half minute, and should then be washed 

 with sterile water. It appears to be safe to simply scrub the area with 

 70% alcohol for one or two minutes. A tourniquet is now applied to 

 distend the vein, and the needle is inserted in the direction of the venous 

 flow. Withdrawing 5 to 10 c.c. of blood, we loosen the tourniquet, 

 then withdraw the needle (otherwise the blood may flow from the 

 puncture), and force out about 1/2 c.c. into the first bile tube, about 

 i c.c. into the second, and 2 or 3 c.c. into the third. It is well to 

 reserve some of the blood for Widal tests. 



The bile tubes are now incubated for 10 to 12 hours and then 

 transfers are made to bouillon tubes. These bouillon tubes can be 

 used in six to eight hours for testing the organism against known 

 typhoid or paratyphoid sera. 



Some prefer to streak plates of lactose litmus agar with material 



268 



