484 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



8. The administration of gonococcus bacterin and antigonococcus 

 serum is likely to be followed by positive reactions. Just how long the 

 antibodies may persist in the blood after a clinical cure has been effected 

 it is difficult to state; at least from six to twelve weeks' time should be 

 given for them to disappear. 



9. In medico-legal cases the courts may not accept the usual evi- 

 dence offered by a bacteriologic diagnosis based upon stained smears of 

 a secretion, and cultures are frequently differentiated from other Gram- 

 negative diplococci, only with difficulty. Conducted with the proper 

 technic, the gonococcus fixation test is highly specific and much less 

 difficult to perform. 



10. Finally, it must be emphasized that the reaction has a far more 

 positive than negative value. The reaction is highly specific, but there 

 is a limit to its delicacy, so that a negative reaction in urethritis does 

 not exclude the possibility of gonococcal infection. 



COMPLEMENT-FIXATION TEST IN GLANDERS 



The complement-fixation test is used extensively by veterinarians 

 in making a laboratory diagnosis of glanders. The test has been found 

 very reliable, and is usually more delicate than the agglutination test 

 and the Strauss guinea-pig test. It has also been used successfully in 

 the diagnosis of human glanders. 



Preparation and Standardization of Antigen. The antigen should be 

 polyvalent, and composed of at least several different strains. Cultures 

 of Bacillus mallei are grown on slants of glycerin agar (1 per cent, acid) 

 for from forty-eight to seventy-two hours. The growths are then 

 removed, and sufficient distilled water added to give a milky suspension. 

 This suspension is sterilized by heating the tubes to 60 C. for two hours. 

 They are then shaken mechanically with glass beads for a few hours on 

 two successive days. Enough sodium chlorid is added to make the 

 solution isotonic, and the whole is preserved with 0.5 per cent, phenol 

 and stored in a dark, cold place, where it will keep for many months. 



A simpler antigen is prepared by growing the bacillus in glycerin 

 bouillon for seventy-two hours, sterilizing by heating to 60 C. for two 

 hours, and preserving with the addition of 0.5 per cent, of phenol. 



The anticomplementary dose is then determined by titration. The 

 antigen is diluted 1 : 20 by mixing 1 c.c. with 19 c.c. of normal saline 

 solution. To a series of seven test-tubes add increasing amounts of 

 diluted antigen as follows: 0.1, 0.2, 0.4, 0.6, 0.8, 1, and 2 c.c. Add 1 c.c. 



