Fermentation of salts of organic acids as an aid to the differentiation of bacterial types / by H.C. Brown, J.T. Duncan and T.A. Henry.

  • Brown, H. C. (Henry Coddington)
Date:
[1924.]
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Licence: Public Domain Mark

Credit: Fermentation of salts of organic acids as an aid to the differentiation of bacterial types / by H.C. Brown, J.T. Duncan and T.A. Henry. Source: Wellcome Collection.

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    [All Rights reserved] THE FERMENTATION OF SALTS OF ORGANIC ACIDS AS AN AID TO THE DIFFERENTIATION OF BACTERIAL TYPES. By H. C. BROWN, C.I.E., M.B., B.Ch., Major, I.M.S. (Reid.), Wellcome Bureau of Scientific Research, J. T. DUNCAN, F.R.C.S.I., D.T.M. & II., London School of Tropical Medicine, AND T. A. HENRY, D.Sc. (Lond.), Director, Wellcome Chemical Research Laboratories. (With Plates I and II.) In the considerable amount of work already done on the decomposition of the salts of organic acids by bacteria, more attention has been directed to the products of metabolism than to the possibility of differentiating bacterial types by this means. Koser (1923), in a recent paper on this subject, gives an exhaustive account of the previous work, and shows that no systematic attempt has been made hitherto to apply the results to the differentiation of bacteria. In the present wmrk it is not proposed to advocate the substitution of organic salts for “sugars” except in those cases in which “sugar reactions” are untrustworthy or fail altogether to differentiate certain serologically well- defined types of bacteria, e.g. those of the Salmonella group, but we think it reasonable to point out that there are two good reasons for such substitution: (1) the purity of the rarer “sugars'- is often doubtful, and (2) the cost of such substances as inositol and trehalose, a diglucose recommended by Jordan (1923), limits, if it does not actually prohibit their use by investigators. Again, the value of aerogenesis, an important feature of sugar fermentation tests, has been impugned by many workers; Ledingham and Penfold (1915) remark that “many paratyphoid strains give little or no gas in the sugars they normally ferment,” and Jordan (1923) states that gas formation in inositol media is very variable and therefore an unsafe basis for judgment. Inositol was employed by Andrewes and Neave (1921) in differentiating the B. paratyphosus B and “Mutton from other types, but they found that one out of twelve “B types and one out of eight “Mutton types failed to ferment this substance, and Jordan (1923) also records discrepancies. It is unnecessary to cite further references here to variations in the fer¬ mentation of “sugars” by bacteria, but those interested in this aspect of the question may be referred to the work of Gurney-Dixon (1919) who quotes the important observations of Penfold, Arkwright and many other observers. Joum. of Hyg. xxm 1