CHAPTER LX 

 BACTERIAL AGGLUTININS AND THEIR APPLICATIONS 



J. G. FITZGERALD and DONALD T. FRASER 



University of Toronto 



The agglutination of bacteria by immune sera is an immunological or serological 

 reaction. All such reactions are specific, relatively or absolutely. Attempts to explain 

 them upon the basis of analogy with physical reactions which in certain respects they 

 resemble leaves out of account their most important characteristic: specificity. 



When agglutinable species of bacteria are appropriately treated with immune 

 sera containing bacterial agglutinins, the individual micro-organisms if suspended in 

 a liquid medium tend to aggregate in clumps or masses and no longer remain discrete. 

 If motile they generally lose their motility. If conditions otherwise are favorable they 

 remain viable. The reaction of bacterial agglutination is relatively specific. It is an 

 antibody-antigen reaction in which the intervention of alexin is unnecessary. It is 

 similar to and perhaps identical with the precipitin reaction. 



EARLY OBSERVATIONS ON AGGLUTINATION 



Charrin and Roger,' in 1889, in a brief communication upon the development of patho- 

 genic microbes in the serum of vaccinated animals, recorded the fact that cultures of Bacillus 

 pyocyaneus when grown in the serum of animals previously injected with cultures of this 

 micro-organism were readily distinguishable from cultures of the same species grown in serum 

 of a normal animal. This difference was described by these observers as follows: "Dans les 

 tubes que nous presentons a la Societe et qui ont ete resemences il y a quatre jours les 

 differences sont encore considerables; on peut remarquer que le serum de I'animal refractaire 

 est clair et transparent; les microbes sont reunis en petits grumeaux, qui s'eparpiUent quand 

 on agite le tube, mais retombent au fond quand on le laisse au repos." 



The significance of this observation was not, it would seem, understood since the only 

 conclusion recorded in this communication by Charrin and Roger was that bacteria behaved 

 differently depending upon whether they were grown in immune serum (blood of vaccinated 

 animals) or in the serum of normal animals. Metchnikoff,^ two years later, observed the 

 clumping action of immune serum upon Vibrio metchnikovii. He did not, however, specifically 

 describe agglutination. In 1893 Isaeff and Ivanoff,^ in a study of the pneumococcus, noted 

 that turbid emulsions of this micro-organism were rendered clear by the addition of pneu- 

 mococcus- immune serum. 



Bordet,^ in 1895, approached the problem in a somewhat different fashion. Cultures of 

 the vibrio of Asiatic cholera were grown upon agar slants, and after twenty hours the growth 

 was washed off with physiological salt solution. He noted that a trace of serum obtained from 

 a rabbit immunized against cholera almost inmiediately immobilized the vibrios, and the 



' Charrin, A., and Roger, C.-H.: Compt. rend. Soc. de biol., 2, 667. 1889. 

 'Metchnikoff, E.: Ann. de Vlnst. Pasteur, 5, 473. 1891. 

 3lsaeff and Ivanoff, M.: Ztschr.f. Hyg. n. Infeklionskrankh., 17, 117. 1894. 

 '• Bordet, J.: Ann. de Vlnst. Pasteur, 9, 462. 1895. 



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