GRUNBAUM-WIDAL REACTION 385 



may be taken as a certain indication of enteric fever. 1 On the other hand 

 a negative result establishes merely a probability that the disease is not 

 enteric fever. A negative result in the early days of a suspected attack of 

 the disease is of less value than one obtained later, for if the disease be enteric 

 fever failure to react is then improbable. But in any case if the result be 

 negative opportunity should always be taken to test the blood again later. 



The reaction may be performed in several ways which are described as 

 slow or rapid according to the time required : but whatever the method 

 adopted the following rules must be observed. 



General rules. 1. For the slow methods the blood must be taken under 

 aseptic precautions from a vein at the bend of the elbow (p. 193), and may be 

 conveniently collected in small sterile glass tubes. For the rapid methods 

 sufficient blood can be collected in capillary tubes by pricking the finger 

 (p. 192). 



2. When the blood has to be sent some distance to a laboratory the tube 

 in which it has been collected should be plugged with a plug of wool passed 

 through the flame. Serum kept in the liquid condition retains its power 

 of agglutination for a very long time. Since, however, drying has no effect 

 on the agglutinating power of the blood, a few drops of the latter may be 

 collected on a piece of paper or on a glass slide and allowed to dry before 

 being sent to the laboratory, and in some cases this may be the more con- 

 venient course to adopt. For purposes of the agglutination reaction the 

 dried blood is dissolved in a drop or two of sterile water. 



In the author's experience good results have always been obtained when the 

 blood was dried on glass but when dried on paper it seemed to lose some of its 

 agglutinating power. Dried blood is only available for use by the rapid method. 



3. The culture should always be examined microscopically to test its purity 

 immediately before being used for the reaction. The mistakes which might 

 arise from the use of an impure culture can be readily appreciated. 



4. The serum must be added to the culture and not vice versa (p. 226). 



A. Slow method. The blood (collected from a vein at the bend of the 

 elbow to ensure that a sufficient quantity is obtained) must be absolutely 

 pure and uncontaminated. and after collection should be set aside in a sterile 

 tube until the clot has separated ; the serum is then drawn up into a Pasteur 

 pipette. 



1. To a tube containing 6-10 c.c. of sterile broth, add ten drops of the 

 serum and sow with a trace of a culture of the typhoid bacillus. A control 

 consisting of a tube of broth containing no serum but sown with a trace of 

 a typhoid culture must, of course, be put up. Incubate the tubes at 37 C. 

 Growth in the tube to which the serum has been added will be somewhat 

 delayed, but small clumps appear after 8 hours or so, and after about 18 

 hours' incubation the appearance is characteristic : the bacilli are collected 

 together at the bottom of the tube in little whitish flocculi, which cannot be 



1 In suspected cases, the possibility of the patient having had previously an attack of 

 enteric fever should always be borne in mind, because if so the blood might still retain 

 some agglutinating power. A few rare cases are on record in which it was found that 

 the blood of persons suffering from diseases other than enteric fever has agglutinated 

 the typhoid bacillus in dilutions of 1 in 100 and 1 in 250. Thus in an undoubted case of 

 pneumonia in a young man in which there was no reason to suspect a previous attack of 

 enteric fever Besson found that the blood of the patient agglutinated the typhoid bacillus. 

 The serum reaction in the absence of enteric infection has also been observed in a case of 

 tuberculous meningitis (E. Mackey) and in a case of abscess of the liver (Megele). In 

 pathological conditions in which the bile enters the blood stream, as for instance in 

 jaundice or occlusion of the bile-duct, the blood may agglutinate the typhoid bacillus 

 (Griinbaum, Zupnik, Kohler and others). 



2B 



