Abstract
The typing of pneumococci is a laboratory procedure which requires a considerable amount of time and for this reason its practical value is greatly minimized. Whether cultures of the organism or white mice inoculations are resorted to, time is a factor that cannot be avoided.
The choice between an agglutination reaction or a precipitation reaction to determine the specific type is rather a personal one, but the writer feels that the latter is in many ways more satisfactory and conclusive.
In pneumococcal meningitis the spinal fluid offers us the means of producing an antigen for a precipitation reaction which is most satisfactory, and permits typing of the pneumococcus present in a very short space of time.
In pneumococci infections of the meninges there are many pneumococci present in the spinal fluid. Whatever amount of fluid is available is centrifuged to throw the organisms to the bottom of the test tube. The fluid is then pipetted from the top, allowing two or three cubic centimeters to remain at the bottom. This is now shaken and we have a concentration of pneumococci much as we would have in a culture many hours old. As the pneumococcus is a bile-soluble organism, we add sodium taurocholate in the proportion of 0.2 of a cubic centimeter of a 10 per cent solution to each cubic centimeter of the spinal fluid retained. It should now be thoroughly mixed by shaking and allowed to stand for from 15 to 30 minutes to allow for the dissolution of the pneumococci. Centrifugation at high speed is again resorted to in order to, clear the solution. It is then carefully pipetted off, not disturbing the sediment at the bottom of the tube.
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