222 MEDICAL BACTERIOLOGY 



An injection is given daily, the dose being increased as rapidly as possible 

 without producing reactions. 



Grow bacillus prodigiosus on agar at room temperature for 10 days. Scrape 

 off the growth with a glass rod and rub to a paste in a glass mortar, using normal 

 salt solution as diluent, bottle and sterilize at 75C. for i hour. Place in ice 

 box. Grow virulent streptococci in bouillon at 37C. for 10 days. 



Determine the amount of nitrogen per cubic centimeter in the prodigiosus 

 paste to ascertain the amount of protein per cubic centimeter and so dilute it 

 with normal salt solution that each cubic centimeter of the vaccine will contain 

 2.5 mg. of protein. 



To each 100 cc. of the bouillon culture of streptococci add 30 cc. of prodigio- 

 sus suspension and 20 cc. of glycerin. Place in bottles, add a crystal of thymol 

 to each and sterilize in a water bath at 75C. for 2 hours. 



HAFFKINE'S VACCINE 



Haffkine's vaccine is made by planting the bacillus pestis in plain bouillon 

 to which sufficient sterile oil or butter has been added to cover the surface with 

 numerous droplets. The culture is incubated at 35C. to 37C. where there is 

 little or no vibration. Growth occurs around and adheres to the droplets of 

 oil, forming white stalactites that hang from the surface as icicles hang from the 

 roof of a tunnel. When a crop of stalactites forms, the flask is shaken and they 

 fall to the bottom. 



The flask is again incubated and a second crop of stalactites forms and is 

 shaken down. 



When the fifth or sixth crop of stalactites has formed the flask is shaken until 

 they are broken up and the bacteria evenly distributed throughout the medium. 

 The flask is then submerged in a water bath and heated at 75C. for 2 hours. 

 The vaccine is then ready for use. 



Haffkine's vaccine is administered to healthy people to immunize them 

 against plague. It confers almost complete immunity to the bubonic but only 

 slight immunity to the pneumonic form of plague. 



Two subcutaneous injections are given, the first 2 cc. to 3 cc. and 10 to 15 

 days later from 3 cc. to 5 cc. 



ANTHRAX VACCINE 



Plain broth cultures are incubated at 42C. until they become avirulent for 

 rabbits and guinea-pigs but are still lethal for mice. From cultures so at- 

 tenuated, vaccine No. i is made, it being a subculture in broth inoculated at 

 37-5C. 



Other cultures are attenuated by incubation at 42C. until avirulent for 

 rabbits but still lethal for both guinea-pigs and mice. From cultures of this 

 attenuation vaccine No. 2 is made, it being 48-hour-old subculture in broth 

 incubated at 37.sC. 



Cattle and sheep are successfully immunized to infection with the anthrax 

 bacillus by two subcutaneous in-jections a fortnight apart. Vaccine No. i is 

 employed for the first injection and vaccine No. 2 for the second. It is not 

 employed in homo. 



