1392 THE ENTEROIDEA GROUP OP TROPICAL FEVERS 



sown in bile -glycerine medium. The method gives good results, but is not 

 advised as a routine procedure. 



Bacteriological Examination of Stools for B. typhosus and Para- 

 TYPHOsus A and B.— a small portion of the stool recently passed and collected 

 into a sterile vessel is smeared on several large MacConkey's agar plates . These 

 are incubated for twenty-four to forty-eight hours at 35° to 37° C, and then 

 any suspicious white colonies further investigated. As is well known, on 

 MacConkey's medium the colonies of coli-like bacteria are red, while those of 

 the typhoid and dysentery group appear whitish. Instead of MacConkey's 

 agar, the Drigalski medium may be used, or Holt-Harris and Teague's methy- 

 lene blue-eosin medium, the inoculation of which may be done from a growth 

 of the faeces in Douglas' peptone-free broth. 



Castellani's Contemporaneous Gas- Agglutination Test. — Twenty 

 tubes of salicin (or raffinose) peptone water, each containing a small fermenta- 

 tion tube, are used, and to each tube 1-2 drops of trivalent typhoid and para 

 A and para B agglutinating serum are added, or i drop of each mono- 

 serum may be added instead of the trivalent one. Each tube is inoculated 

 from one of the lactose non-fermenting white colonies present on the MacConkey 

 plates made from the suspected fsecal matter. The tubes are placed in the 

 incubator at 35°-37° C. for twelve to twenty-four hours and then examined. 

 All tubes showing diffuse turbidity or gas, or both, are discarded. If one (or 

 several) of the tubes shows agglutinated growth as well as absence of gas a 

 diagnosis of enteric may be made, at once, for practical purposes. 



If the search is limited only to typhoid and not para A or para B, it is better 

 to use glucose-peptone-water tubes slightly tinged with litmus, to which 1-2 

 drops of typhoid agglutinating monoserum have been added. If one of the 

 tubes (ot several) shows agglutination and absence of gas while the medium 

 has taken a reddish colour (acidity), the diagnosis of typhoid may be made. 



Castellani's Poliserum Method. — This is an application of Castellani's 

 general method to isolate a bacterium from a mixture of other bacteria by 

 using a multivalent serum which will agglutinate and delay the growth of all 

 or most of the bacteria present, while it does not influence the growth of the 

 germ or group of germs one desires to isolate. Great difficulty, however, is 

 found ,in practice in preparing such a serum, the best method of preparation 

 being that of mixing several plurivalent sera. The poliserum method may 

 be carried out in various ways. Two may be mentioned: — 



1. {a) Inoculate with the faecal matter to be investigated several tubes of 

 taurocholate of soda peptone water, or Browning, Gilmore, and Mackie's 

 telluric acid peptone water may be used. 



(b) Immediately after, or better immediately before, the inoculation, add 

 3 drops polyvalent lactose-fermenting-intestinal-bacteria serum, 3 drops poly- 

 valent non-lactose fermenting faecal bacteria serum {B. proteus group, etc.), 

 taking care to use serums containing only a very small amount of typhoid 

 coagglutinin; or serums can be used from which the typhoid coagglutinin has 

 been removed by absorption. 



(c) Incubate for twelve or twenty-four hours, then make plates on Mac- 

 Conkey, Conradi-Drigalski, or similar media, from the most superiicial portion 

 of the liquid medium, and investigate further any suspicious colonies which 

 may develop, testing them with typhoid, paratyphoid A, and paratyphoid B 

 serums, etc. When there are many flocculi of agglutinated bacilli also in the 

 upper portion of the tube, these may be got rid of by a short centrifugation. 

 A short centrifugation with an ordinary electric centrifuge will cause the agglu- 

 tinated bacilli to fall to the bottom, while it has practically no effect on the 

 non-agglutinated germs in young cultures. 



2. Instead of inoculating the suspected fsecal matter direct in taurocholate 

 peptone water and poliserum, the stool is plated on MacConkey's medium. 

 After fifteen to twenty-four hours' incubation at 35°-37° C. all the white 

 colonies (lactose non-fermenters) are inoculated in a tube of peptone water, 

 to which has been added 2-3 drops of the poliserum for lactose non-fermenters 

 apart from enteric group. After fifteen to twenty-four hours' incubation 

 the growth from the top of the tube is further investigated. 



