542 PATHOGENIC MICROORGANISMS 



sickrate with the reduction of carriers, focusing the carrier ex- 

 aminations upon the small epidemiologically determined intimate 

 group from which the case has come, rather than making wholesale 

 carrier examinations of carriers of meningococcus through whole 

 regiments and divisions. 



Carrier Determination. The bacteriological analysis of a carrier 

 is not a simple procedure, and implies the proper control of a great 

 many conditions which necessitate special description. 



To obtain the material properly the swab must be taken from 

 high up in the pharynx, behind the soft palate. A general swabbing 

 of the pharynx and throat is not sufficient. The best swabs for this 

 purpose are made by the West tube method, as follows: A cotton 

 swab is fixed on the end of a copper wire, about eighteen centimeters 

 long, and this is inserted in a glass tube, bent upward at the swab 

 end, in such a way as to permit passage upward behind the soft 

 palate. The swab is placed into the tube, both ends plugged with 

 cotton, and is so sterilized. For large scale work it is sufficient 

 to take copper wire swabs, sterilize them in a box, and bend them 

 up carefully with the finger, being careful not to touch the cotton, 

 just before use. Swabbing through the nose has also been practiced, 

 but we do not believe that it is as efficient as the method described 

 above. The swab must be taken with the patient facing the light. 

 A tongue depressor is used, and the swab inserted so as to pass 

 behind the soft palate. The copper wire is then thrust forward 

 so that the swab emerges from the tube and touches the posterior 

 and upper pharyngeal wall. Slow motion to and fro brings the 

 cotton in contact with the sides of the upper pharynx. The swab 

 is then immediately passed over the surface of the plate medium. 

 It is best not to carry the inoculated swab back to the laboratory, 

 but to plate it directly upon removing the material from the patient. 



The media employed are various, but for ordinary use a glucose- 

 hormone-agar, P H of 7.4 with addition of 1-10 defibrinated or 

 hemolyzed human or rabbit's blood, is best. The plates thus 

 inoculated should be kept warm and immediately taken to the 

 laboratory where they are incubated. The British prefer trypagar 

 to the hormone agar as the basic medium for such work. 



After eighteen to twenty-four hours incubation, the plates are 

 examined and the colonies suspected of being meningbcocci are 

 fished. This is not a matter which can be taught by book. The 

 colonies are of small, rounded appearance, the recognition of which 



