Diphtheria / by William P. Northrup ; measles, scarlatina, German measles / by Theodor von Jürgensen ; ed., with additions by William P. Northrup ; authorized translation from the German, under the editorial supervision of Alfred Stengel.

  • Northrup, William P. (William Percy), 1851-
Date:
1902
Catalogue details

Licence: In copyright

Credit: Diphtheria / by William P. Northrup ; measles, scarlatina, German measles / by Theodor von Jürgensen ; ed., with additions by William P. Northrup ; authorized translation from the German, under the editorial supervision of Alfred Stengel. Source: Wellcome Collection.

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    at a temperature of 36° to 37° C. (96° to 99° F.). It may grow at a temperature of 41° C., according to Park. Growth on Blood-serum.—^This is the most favorable medium for the growth of the bacilli (for preparation of this serum see page 137, Antitoxin) and is the usual medium chosen for cultures taken for diagnostic purposes. After twelve hours’ growth the colonies are seen as small, round, slightly elevated points, whitish-gray, or more rarely yellowish, in color. The borders of the colonies are somewhat uneven. After twenty-four hours they .attain a diameter of 14 to //; after two days, to 3 a. If widely separated, they may attain a diameter at this time of -J- of an inch. If the serum is moist, the contiguous colonies may coalesce. The colonies do not liquefy the serum. Growth on Agar.—On 1 % slightly alkaline, plain, nutrient agar or glycerin-agar the growth is less characteristic and luxuriant than on blood-serum. It has been found that bacilli taken directly from the throat grow poorly or not at all on this medium. Pure cultures, however, grown first on some other medium show a fairly luxuriant growth. Different preparations of agar vary as to their suitability for the growth of the bacilli. The medium, at any rate, to get the best effects, should be rendered alkaline. The agar colonies on the surface generally show a lateral extension on one or both sides, exceeding in extent the colony itself. The deep- growing colonies, as a rule, present no such extension, but are round or oval. The surface colonies are often granular, usually showing a dark center. Their thickness is variable; the edges are irregular, and some- times delicately fringed, or, again, rounded and smooth. The colonies are gray or grayish-white. Agar cultures are usually employed to obtain cultures of pure diph- theria by plating. For this purpose the colonies supposed to be diph- theria bacilli are taken from a blood-serum culture and streak cultures made on the freshly prepared agar plates, which are then allowed to incubate for twelve hours. Growth in Bouillon.—The diphtheria bacilli grow readily in alkaline bouillon, with or without a small amount of glucose; also in slightly acid and neutral bouillon. According to Madsen, in acid bouillon the acidity increases rapidly for five or six days, when it ceases to increase, evidently owing to the fact that the degree of acid- ity then formed is unsuitable for further development of the bacilli. In four or five days there is a diffuse cloudiness in the bouillon and a film on the surface, the latter increasing in thickness for a long time. On shaking the flask, part of the film falls to the bottom and adds to