TYPHOID FEVER 101 



For use, add 5 c.c. of (i) and the same amount <)fX2) 

 peptone-salt-water, shake well, and allow to stand for a few minutes : 

 a rose-red colour will be formed if indol is present. 



Having determined the reactions of the culture on these media, refer 

 to the table, which is modified from Henderson Smith, and determine 

 the nature of the organism. The last steps are to determine the serum 

 reactions. This is done in two ways, the first of which has been 

 mentioned already. Take a specimen of standard agglutinating serum 

 to the organism which you believe to be present and determine its 

 power on a typical living culture of the organism. This can be done 

 either by the drop method in Dreyer's tubes or by means of capillary 

 pipettes : it is necessary to reach the upper limit at which the serum 

 will act. Then test the action of the same serum on the culture you 

 have isolated : if your diagnosis of its nature is correct, it should be 

 agglutinated at approximately the, same dilution of serum. 



The power of the culture to absorb specific agglutinins from the 

 serum is then tested. Take a well-grown agar slope, twenty-four hours 

 old, and add a few drops (about four, the amount depending on the 

 amount of growth), and mix the two thoroughly together. Pipette off 

 the emulsion, put it in a small sterile tube, and incubate for twenty-four 

 hours at 37 C. Then centrifugalize and pipette off the clear super- 

 natant fluid. Lastly, put this up in a i in 10 dilution against a standard 

 agglutinable culture of the organism in question, incubating for two 

 hours at 50 C., and reading off the result after fifteen minutes in the 

 cold. Thus if you have isolated an organism giving the cultural and 

 chemical characters of the typhoid bacillus, you find it removes all the 

 specific agglutinins from a powerful antityphoid serum, so that the 

 latter will no longer agglutinate a standard culture of typhoid bacilli, 

 the diagnosis is settled. The same applies, mutatis mutandis, with 

 the other organisms. 



MALTA FEVER 



This disease occasionally causes mistakes in diagnosis in 

 this country, and its existence should be remembered in deal- 

 ing* with patients who have travelled, especially in the neigh- 

 bourhood of the Mediterranean, and who suffer from chronic 

 fever of obscure nature. The diagnosis may be made either 

 by means of a blood-culture (see p. 194), or more conveniently 

 by means of an agglutination reaction, a culture of the 

 organism (Micro coccus melitensis) being used. There is no 

 especial difficulty about the technique, but it is advisable 

 always to test the culture used with two or three specimens 

 of normal blood, as various strains of the organism are found 

 to differ greatly in sensitiveness. If the culture to be used 

 is found to clump with normal blood, it may still be used for 



