70 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



the disease — i.e., within the first week. Thus it is available before 

 the Widal reaction appears, and should be used wherever a 

 positive diagnosis is required at a very early date. The blood is 

 drawn direct from a vein by one of the methods described on 

 p. 144, and at least 5 c.c. should be taken, whilst 10 c.c. gives a 

 greater probability of a successful result. The best culture 

 medium to employ is broth to which '5 to i per cent, of sodium 

 citrate has been added ; this prevents the coagulation of the 

 blood and the consequent entanglement of the bacilli in the clot, 

 which, when it occurs, greatly delays the appearance of the 

 growth. The amount of blood indicated above should be 

 inoculated into loo c.c. of citrated broth and incubated at 37° C. 

 Growth will probably be seen in twenty-four hours or less. Un- 

 fortunately, typhoid bacilli fresh from the body often fail to 

 agglutinate with typhoid serum, and only acquire that property 

 after cultivation for several generations on artificial media : this, 

 the best test, is not always conclusive. But all cases clinically 

 resembling early typhoid which give a culture of motile, non- 

 sporulating. Gram-negative bacilli of the morphological characters 

 described above, should be regarded as early typhoid, and in all 

 probability the appearance of the Widal reaction will soon settle 

 the matter. The other possible diagnoses are extremely unlikely. 

 The further identification of the bacillus is a matter of some 

 difficulty for which expert help should be obtained, or one of the 

 larger manuals of bacteriology consulted. 



The mesenteric glands and liver are, of course, not available 

 or the purpose of diagnosis. 



The demonstration of the bacilli in the urine is sometimes quite 

 easy, and might be of some diagnostic value. But they do not 

 always occur in this excretion, and the B. coli often does so, and it 

 is not easy to distinguish between the two. 



The only way in which typhoid fever can be diagnosed with 

 ease and certainty by a demonstration of the specific bacillus is 

 by an examination of material drawn directly from the spleen by 

 means of a hypodermic needle. The organism occurs constantly in 

 this situation, and its demonstration is not difficult. The necessary 

 operation, however, is by no means devoid of risk, and is now 

 generally abandoned. 



This brings us to the method in which typhoid fever is now 

 usually diagnosed by the bacteriologist — Widal's reaction. This 



