SOCIETY OF AMERICAN BACTERIOLOGISTS 



Abstracts of Papers 



Presented at Seventeenth Annual Meeting, Urhana, Illinois, 

 December S8 to SO, 1915 



SYSTEMATIC BACTERIOLOGY 

 Under Supervision op S. H. Ayers 



Studies on the Classification of the Colon-Typhoid Group. C.-E. A. 



WiNSLOW AND I. J. KlIGLER. 



The committee on the classification of the colon-typhoid group, 

 appointed at Philadelphia, has adopted a standard series of tests for 

 titrable acidity, hydrogen ion concentration, milk reactions, indol 

 production, gelatin liqefaction and chromogenesis. This preliminary 

 report is based on the application of certain of these tests to 150 strains 

 from the American Museum of Natural History collection; each strain 

 being tested independently in New Haven and in New York. 



Our results so far indicate that there are at least three major groups 

 in the colon-typhoid scries, the B. coli group clotting milk and producing 

 a final high hydrogen ion concentration in glucose broth and forming 

 indol; the B. aerogenes group, clotting milk but producing a final low 

 hydrogen ion concentration in glucose broth and failing to form indol; 

 and the B. typhi group giving a final alkalin reaction in milk but yield- 

 ing a high hydrogen ion concentration in glucose broth and failing 

 to form indol. The B. coli group includes at least three types, B. com- 

 munis (indol positive, sucrose negative) — B. communior (indol posi- 

 tive, sucrose positive) and B. acidi-lactici (indol negative, sucrose 

 variable). The B. aerogenes group is generally indol negative and 

 sucrose positive and includes the gelatin liquefying B. cloacae as well 

 as the typical B. aerogenes. The B. typhi group is indol negative 

 and includes at least three types — B. dysenteriae (reaction in milk 

 varying back and forth about the neutral point), B. typhi (initial 

 acidity followed by alkalinity), and B. paratyphi (alkaline throughout). 



The indol reaction as determined by the use of a tryptophane medium 

 with 71 strains, gave results identical with those obtained by the 

 use of peptone on the same strains two years ago. A positive Voges and 

 Proskauer reaction is correlated with negative indol and a negative 

 methyl red test for hydrogen ion concentration and clearly marks off 

 B. aerogenes as a distinct group (the high gas ratio cultures of 

 Rogers and Clark). 



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