528 PATHOGENIC MICROORGANISMS 



which is always under some pressure, is taken directly into a centri- 

 fuge tube. This fluid must then be examined as above indicated in 

 the technical section on spinal fluid, and the diagnosis made. If pos- 

 sible, a smear should be made at the bed side, and an immediate Gram 

 stain done with the first drop of fluid that flows. In this way, it 

 may be possible to inject the first dose of serum immediately after 

 the withdrawal of the diagnostic fluid. 



Examination of Spinal Fluid. The spinal fluid of meningococcus 

 cases is slightly turbid in the very early periods, becoming increas- 

 ingly purulent, with large numbers of polymorphonuclear leucocytes. 

 In some cases the fluid which has been very purulent may clear 

 up considerably, and then become purulent again, a matter probably 

 dependent upon sacculation in parts of the subarachnoid space. The 

 fluctuations in the nature of the spinal fluid under intraspinous 

 serum treatment will be spoken of in another place. A certain 

 amount of prognostic information can be obtained from the spinal 

 fluid in that in severe cases that are not doing well, there will be 

 a considerable number of organisms, extracellular. Ordinarily, the 

 majority of the meningococci are intracellular. Such spinal fluid 

 should be taken into sterile centrifuge tubes, brought to the labora- 

 tory without delay, slides smeared from the sediment, and stained 

 by Jenner and by Gram. It is important to remember that because 

 of the extensive autolysis of meningococci in the fluid, it may 

 under circumstances be very difficult to find meningococci. In such 

 cases, if prolonged search has failed to reveal organisms, our ex- 

 perience has taught us to assume that purulent fluid from a case of 

 an acute meningitis in which there are a preponderance of poly- 

 morphonuclear leucocytes without organisms is probably " meningo- 

 coccus " in origin. Streptococcus and pneumococcus fluids invariably 

 show Gram-positive cocci. 



The fluid should be cultured upon blood agar plates, the medium 

 prepared as described above. It is well to inoculate the plates 

 heavily since the viable organisms present, even in acute fluids, 

 may be relatively few in numbers. To be on the safe side it is 

 sometimes well too, to place a portion of the fluid in the original 

 centrifuge tube in the incubator for three or four hours before 

 inoculating media from it. 



The typing of meningococci derived from spinal fluid is desirable 

 since the preliminary injection of polyvalent serum upon first diag- 

 nosis may be advantageously followed by the injection of type sera, 



