BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP 653 



Twenty-first day to convalescence, sixteen cases examined; typhoid 

 bacilli isolated from thirteen; percentage of positive cases 81.2 per cent. 



Stool Examination and Method of Typhoid Carrier Detection. 

 Fecal carriers of typhoid bacilli may be detected by cultural methods 

 applied either to specimens of feces or to duodenal contents, obtained by 

 a tube passed through the stomach into the duodenum. The simplest method, 

 of course, is direct examination of the feces. The duodenal tube, however, 

 will probably be used considerably in the future, since in some cases it may 

 be positive when stool cultures are negative. As a matter of fact, in the hands 

 of Garbat 31 and Nichols, 32 the duodenal method seems to have given more 

 regular results than the stool method. 



Stool Examinations. Stool material for typhoid examination should be 

 fresh. Preserving stools for as long as twelve hours will diminish positive 

 findings by 50 per cent. If large numbers are to be examined, it is 

 a good plan to give mild, saline cathartics in the morning, so that all 

 specimens can be collected at about the same time. It is best to collect 

 specimens by cotton swabs, on swab sticks thrust into tubes in which there 

 are a few drops of salt solution to prevent drying. We have found that 

 rectal swabbing, if properly carried out, may be a valuable method of collect- 

 ing material. If it is absolutely necessary to ship stools some distance, the 

 addition of 20 per cent glycerin is of advantage. 



A suspension of about one part of feces to twenty-five parts of salt 

 solution is made, thoroughly emulsified, and allowed to stand to allow the 

 large particles to settle. With this material, surface smears are made with 

 a glass rod upon plates of either Robinson and Rettger's modification of 

 Endo's medium, or Krumwiede's brilliant green medium, as described in the 

 section on media. It is of advantage to use the large plates. A bent glass 

 rod is dipped into the emulsion and rubbed over the surface of a plate, 

 beginning in the center, by passing in concentric circles so that the entire 

 plate is gently smeared. A second plate is inoculated in the same way, 

 without redipping. It is sometimes well to make similar plates with a 1 : 5 

 dilution of the original suspension. 



Plates for this purpose should be poured and allowed to dry on a laboratory 

 desk for a few hours before use, and should be kept in the dark if Endo's 

 medium is used. Great care in the accurate production and testing out of 

 the media, should be taken as indicated in the section describing these media. 

 The plates should either be inverted in the incubator, or else earthen-ware 

 covers should be used. Large pieces of blotting paper inserted under the 

 lid serve the same purpose. 



31 Garbat, The Typhoid Carrier Problem, Monographs of the Rock. Inst., in press. 



32 Nichols H. J., Jour. Exp. Med., xxiv, 1916, 497; Jour, of A. M. A., 

 Ixviii, 1917, 958. 



