BACTERINS (VACCINES) 95 



CHAPTER XV 

 BACTERINS (VACCINES) 



Bacterins are sterilized suspensions of bacteria in normal 

 saline solution. The term vaccines or bacterial vaccines is 

 frequently but erroneously used in place of bacterins, as the 

 word vaccine relates to a cow or calf. Bacterins are used in 

 the treatment of localized infections, and especially those of 

 a chronic nature, and have been employed extensively to es- 

 tablish immunity against infection. The best example of 

 this is the immunization of armies and inmates of institu- 

 tions against typhoid fever. 



Preparation. The organism is grown on the surface of 

 the most appropriate medium, usually agar-agar, until an 

 abundant growth is present. This ordinarily requires 

 twenty-four hours. The growth is then washed from the 

 medium with sterile normal saline solution, and collected in 

 a small sterilized flask or bottle containing glass beads and 

 shaken to break up clumps. A sterilized glass bulb, drawn 

 to a point (a test-tube drawn out answers as well), is filled 

 with the resulting emulsion, the end sealed in a flame, and the 

 bulb immersed in a water-bath at 60 C. for one hour. The 

 neck of the bulb is then broken, and a few drops of the emul- 

 sion sown on culture-media to determine the presence or ab- 

 sence of living organisms. 



Standardization. The number of bacteria in a cubic cen- 

 timeter of the mixture is determined as follows: a portion 

 of the emulsion is reserved unheated, and at once mixed 

 with an equal volume of blood by aspirating into a capillary 

 tube any quantity, usually a column 2.5 cm. long, of the 

 emulsion, followed by an equal volume of blood. The blood 

 and emulsion are then mixed on a glass slide and thin smears 

 are made. After air drying, the films are fixed with satur- 

 ated solution of bichlorid of mercury and stained with car- 

 bolthionin. 



