74 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



those which are in use for the other diseases mentioned — i.e., by 

 the demonstration of the specific organism. Suppose, for instance, 

 that we were to attempt to determine the nature of a case of 

 diarrhcea by a search for the typhoid bacillus in the stools. For 

 every typhoid bacillus which we should encounter we should find 

 a great many colon bacilli, and we should only be able to dis- 

 tinguish the one from the other by a prolonged and careful 

 examination of pure cultures. It is quite certain that the disease 

 ■might be diagnosed in this way ; indeed, it has been done, but the 

 task is an extremely difficult one, and the diagnosis would be 

 delayed for a considerable period.* 



In other regions in which the typhoid bacillus occurs during an 

 attack of typhoid fever the search is usually facilitated by the 

 absence of other organisms, especially by the absence of the 

 B. coli. The specific bacillus occurs in the blood, spleen, spots, 

 mesenteric glands, liver, and frequently in the urine. 



It may often be demonstrated in the blood, and the method is 

 now acquiring some importance from the fact that positive results 

 are found to be very frequent if the examination is made early in 

 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. 163, 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 0-5 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 100 c.c. of citrated broth and incubated at 37° C. 

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

 fortunately, typhoid bacilH 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 



* Modern methods have greatly facilitated the task, but even now it is only 

 used when other methods are unavailable, or for certain special purposes. 



