Abstract
Differentiation of Salmonella pullorum from Salmonella gallinarum cannot be made by agglutination or agglutinin-absorption, because of a similar antigenic structure. This similarity and the fact that the 2 diseases produced in fowls are alike in some respects have caused certain European investigators 1 , 2 , 3 to consider them as variants of the same species.
Mailman's 4 work on the use of sodium-mucate agar, Jordan and Harmon's on tartrate-agar, 5 and Naidu's 6 and Nobreg's 7 studies on differentiation by bacteriophage, are examples of investigations which supply further evidence that these organisms are separate entities. This report deals mainly with the use of cysteine-gelatin as another differential medium.
The cysteine-gelatin was prepared according to a method used by-Valley 8 for the study of anaerobic growth. Enough Difco granular gelatin is added to the 0.15% cysteine-broth described by Valley 9 to make a 12% solution. After dissolving the gelatin in a water-bath, the medium is tubed and sterilized at 15 pounds extra pressure for 15 minutes. Tubes of 12 mm. and of 16 mm. diameter were found to be equally satisfactory, when at least 5 cc. of medium were used. The cysteine-gelatin retained its potency for at least 2 months, when stored in the refrigerator and dehydration was prevented.
The action of 61 strains labeled S. gallinarum, 120 S. pullorum, and 11 S. typhi, was studied in this medium. Tartrate-agar 5 was inoculated with the same strains, for comparative purposes. A summary of these results is given in Table I. The tartrate-reactions support Mailman's findings. The results obtained with the 11 strains of Salmonella typhi are included also for record. Kauffmann and were designated “Duisburg.”
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