390 THE TYPHOID BACILLUS 



its means it is possible to determine whether agglutinins which have been 

 detected in a suspected typhoid serum are specific agglutinins or co-agglu- 

 tinins. (For technique see p. 436.) 



9. Complement fixation. 



The method of complement fixation (Bordet-G-engou reaction) is applicable 

 to the diagnosis of enteric fever and to the identification of the typhoid 

 bacillus. The method is described at p. 233. The results are more exact 

 and more reliable than agglutination (Widal and Le Sourd) and the reaction 

 gives positive results with the serum of " carriers " even when no bacilli 

 can be detected (Scheme). 



[H. K. Dean finds that the complement-fixation method affords an extremely 

 delicate and specific means of differentiating between various members of the 

 typhoid and paratyphoid group. (For Dean's technique see p. 428).] 



SECTION IV. DETECTION, ISOLATION AND IDENTIFICATION OF 

 THE TYPHOID BACILLUS. 



The detection of the typhoid bacillus may be rendered difficult by the 

 presence of other organisms in the fluid or tissue under examination. Thus, 

 in patients suffering from enteric fever or in patients or animals who have 

 died from the infection the bacillus occurs in pure culture and can be readily 

 isolated, but when it is necessary to isolate it from water, dust, stools, etc. the 

 presence of the colon bacillus often renders the investigation by no means easy. 



The methods of isolating the typhoid bacillus from water and other sources 

 is dealt with in a separate chapter (Chap. XXIII., p. 401) and here the more 

 simple investigations only will be considered in which the organism is assumed 

 to be in pure culture in a fluid or tissue of the body. 



1. Microscopical examination. 



For purposes of microscopical examination films and sections of the spleen 

 and other organs as well as in the case of experimentally infected animals 



FIG. 221. Typhoid bacillus. Section of a spleen. Carbol-thionin. 

 (Oc. 2, obj. T Uh, Zeiss.) 



films from the pus of typhoid abscesses and the peritoneal exudate, should 

 be made. 



