Because of the disadvantages known to be inherent in all the methods used for typing pneumococci by means of sputum or urine, we attempted to devise a method which should be based on the use of the blood of the patient. We finally adopted the procedure described herein. It had been pointed out by Rosenow,1 and later by Longcope,2 that pneumococci produce a coagulum when grown in the serum of patients suffering from pneumonia, the clot formation being due to the production of acids, probably from glycoproteins, in the serum. This property—manifested in a different way—we have found to be specific, not only for pneumocicci as a group, but also for the various pneumococcus types. A full discussion of the theory of the reaction is reserved for another time.
Ten c.c. of blood are drawn with sterile precautions into test tubes containing a few crystals of potassium
LOEWE L, HIRSHFELD S, WALLACH K. A NEW METHOD FOR TYPING PNEUMOCOCCI BY THE USE OF BLOOD. JAMA. 1919;73(3):170–171. doi:10.1001/jama.1919.02610290012005
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