Memoranda concerning vaccination in the prophylaxis of typhoid fever.

  • Magill, William S., 1866-
Date:
[1912]
Catalogue details

Licence: Public Domain Mark

Credit: Memoranda concerning vaccination in the prophylaxis of typhoid fever. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    urn virulent strain of bacillus typhosus, inoculated upon a broad surface of the usual agar media, the culture then incu- bated for forty-eight hours, the resultant growth of bacteria being then washed off with sterile physiological salt solution, in which solution the number of typhoid ba- cilli per c.c. is then determined by the method subsequently to be described, and this solution then diluted with the same physiological salt solution to make a solu- tion of standardized bacteria per c.c. Two strengths of solution are made: (A) in which the solution contains 500,000,000 ty- phoid bacilli per c.c; and (B), solution which contains 1,000,000,000 typhoid bacil- li per c.c. The German method of producing the typhoid vaccine is that followed in the lab- oratory of the United States Army Ser- vice. The English method of producing the typhoid vaccine is somewhat different, as it was devised by Wright and slightly per- fected by Leishman. The method consists in inoculating a carefully prepared buillon of standardized alkalinity of 10 (Eyre scale) with a usual not particularly viru- lent strain of typhoid bacillus. The cul- tures are then grown in flasks, affording as large surface as possible, in the incubator at blood temperature, from twenty-four to forty-eight hours, preferably the latter. When grown under such conditions, the usual strain will produce at the end of forty-eight hours a culture of which each c.c. will contain something over 1,000,000,- 000 typhoid bacilli, perhaps 1,500,000,000. The actual number of bacilli contained in these growths is then determined by the process devised in Wright's laboratory and carried out very simply as follows: It is recalled that the number of red blood corpuscles in human blood is well known and varies slightly. If, therefore, an equal volume of such blood be mixed with equal volume of culture or emulsion of typhoid bacilli, the resultant mixture may be smeared upon a slide, stained with any good blood stain, and the relative num- ber of bacilli to that of red blood cor- puscles is then easily determined by a small microscopic examination, counting the ba- cilli and red corpuscles in one or more fields observed. Having determined this proportionate count, the actual number of bacilli per c.c. in the culture examined, results from a simple calculation. The culture or emul- sion of typhoid bacilli to be standardized, is then properly diluted according to the determined count to bring the actual num- ber in the diluted blood to any desired standard. This method is utilized at pre- sent for all standardization of typhoid ba- cilli cultures or emulsions used as vaccines. Referring then to the English method of typhoid vaccine production, the cultures previously obtained are standardized by the methods just described to two dilu- tions: A—containing 500,000,000 typhoid bacilli per c.c, and B solution—containing 1,000,000,000 of these germs per c.c The third prominently proposed vaccine varies substantially from either the Ger- man or English vaccines just described. The third vaccine is advocated most strong- ly by Vincent and contains elements which may prove to make it superior to the other two, but Vincent's vaccine has not had any- thing like the broad, extensive application in actual prophylactic work. Vincent's method involves the culture of many selected strains of typhoid bacilli in his effort to produce a polyvalent vaccine. The selected strains are inoculated all to- gether upon the usual agar and grown in the incubator for forty-eight hours, ex- actly as in the case of the German method. The resultant growth is carefully washed off with physiological solution, as in the German method, but this resultant emul- sion of typhoid bacilli is then incubated at blood temperature to secure an effective maceration and the effusion of the endo- bacillary substances into the fluid. The macerated fluid is then centrifugalized and the resultant super-natant, clear liquid is removed from all sediment and shaken up with ether. The ether is utilized here as an ultimate sterilizer, as Vincent avoids any application of heat to his vaccine be- yond that of blood temperature. After agitation with ether, the heating of this fluid to blood temperature brings about the rapid ether removal by evapora- tion and the clear liquid remaining consti- tutes the third vaccine, which is that advo- cated by Vincent. Of this third vaccine, two strengths are