VACCINATION 381 



a sterilized culture * the serum acquired bactericidal and agglutinating 

 properties for the typhoid bacillus. 



Since then numerous methods of antityphoid inoculation have been devised, 

 some based on the inoculation of " whole " cultures (Pfeiffer and Kolle, 

 Wright, etc.) others on the use of extracts made from the bodies of the bacilli. 

 Finally, Besredka has conceived a method of vaccinating with bacilli 

 sensitized with antityphoid serum. 



1. Methods based on the use of "whole" cultures. 



(a) The Wright-Leishman method. Wright's original method has been 

 modified in view of the experiments of Leishman and Harrison. Wright 

 now uses a bacillus of low virulence which he grows at 37 C. for 24-48 hours 

 in a shallow layer of peptone broth to facilitate aeration, sterilizes by heating 

 to 53 C. for an hour (not at 60 C. as in his original method), and then adds 

 O25 per cent, of lysol to ensure its sterility. 



Two inoculations into the outer surface of the arm or over the pectoral 

 muscle are given : the first of 500 million bacilli (0'5 c.c. of vaccine), the 

 second 10 days later of a 1000 million bacilli (1 c.c. of vaccine). 



The doses prescribed by Wright and Leishman should be scrupulously observed : 

 too small a dose will fail to produce immunity and too large a dose will be followed 

 by a sharp reaction and may fail to vaccinate (Wright, Paladino-Blandini). It is 

 therefore necessary to enumerate the bacillary content of the vaccine in order to 

 standardize it. 



Standardization of the vaccine. Mix a measured volume of vaccine with an 

 equal volume of a known dilution of blood, make a film, stain and count the number 

 of bacilli and red cells in several fields of the microscope. The number of red cells 

 per cubic centimetre being known, the number of bacilli is easily calculated. 



(/3) Pfeiffer and Kolle 's method. Cultures on agar 24 hours old are scraped 

 with a platinum needle and the growth mixed with saline solution (45 c.c. for 

 ten tubes). The emulsion is filtered through gauze, the filtrate is heated to 

 60 C. for 2 hours, then distributed in tubes and a little carbolic acid added. 

 The quantity to be used for the first dose is 0'5 c.c. (corresponding to 1 loopful 

 or 2 milligrams of fresh culture or y^th of an agar culture) : 8 or 12 days 

 later a second dose of 1 c.c. is given. A third dose may with advantage be 

 given ; if this be purposed it is well in order to obviate any violent reaction 

 to use smaller doses viz. : 0'3 c.c., 0'8 c.c., and 1 c.c. 



(7) Bassenge and Rimpau's method. These authors adopt a technique 

 similar to that of Pfeiffer and Kolle, but to avoid too violent a reaction 

 they give four inoculations of very small quantities with an interval of 10 

 days between each : for the first inoculation a dose equal to ^th of a loopful 

 is given and then successive doses of y-th, Jth, and ith of a loopful. 



(S) Friedberger and Moresehi's method. A minimal quantity ( T ^th or 

 ToVoth of a loopful) of an eighteen-hour culture on agar dried and heated to 

 120 C. for 2 hours is inoculated intra-venously. A single inoculation is 

 sufficient but the intra-venous does not seem as harmless as the sub-cutaneous 

 method and is followed by a violent reaction. 



2. Methods based upon the use of bacillary extracts. 



The active principle of the typhoid bacillus can be extracted by the different 

 methods which have been studied under the head of typhoid toxin : macera- 

 tion, trituration, freezing, etc. Methods of antityphoid vaccination based 



1 At first it was the custom to use very virulent bacilli. Wassermann has shown that 

 there is no direct and constant relation between toxigenic and immunizing power : he 

 suggests the use of a polyvalent vaccine prepared with a mixture of many strains of 

 typhoid bacilli ; such a vaccine is said however to have no advantage over a monovalent 

 vaccine (Bassenge and Mayer). 



