METHODS OF MAKING BACTERIOLOG ICAL EXAMINATIONS. — An immediate microscopical examination of the exu date in cases of suspected diphtheria will often justify a positive diagnosis. A bit of membrane removed from the throat by a swab is smeared upon a cover-glass or slide, dried, fixed by heat, and then stained with Loeffler's methy lene-blue solution.
With an oil immersion lens we may then be able to determine the presence of bacilli sufficiently characteristic to warrant a positive diagnosis. The ba cilli under such conditions do not have the characteristic features which are presented by cultures upon suitable media. They are much more irregular in size, shape, and staining properties. Positive judgment is, therefore, much more difficult and uncertain. Failure to find the bacilli by this method would in no way prove that the case was not diphtheria. The uncertainties of the method are so pronounced that it is rarely employed.
Method adopted by Chicago Health Department for making early diagnosis of diphtheria consists in spreading a little mucus fro/n the throat on a slide, allowing it to dry, then staining and examining microscopically immediately. In about 50 per cent. of cases a suffi cient number of bacilli is found to war rant a diagnosis. In case the Klebs Loeffler bacilli cannot be found in this way, patients lose little by waiting for incubation of cultures. During four years the mortality of 3S per cent. from diphtheria. not including laryngeal cases, has fallen in Chicago to 6.7 per cent., in chiding all forms of the disease. This is thought to be due to the improved methods by which early diagnosis is made possible, and the early use of anti toxin. W. K. Jaques (Jour. Amer. Med. Assoc., Oct. 29, '9S).
Diphtheria bacilli and other bacilli sometimes identical in appearance with the diphtheria bacilli, and sometimes so short and round as to be indistinguish able from cocci, found in tuberculous lungs. A diagnosis of throat affection, therefore, should not be made wholly from results of a simple smear-prepara tion, without proper cultures. In num
ber of cases none of the patients had had diphtheria, but inoculating lower aninials with the bacilli produced effects similar to those of the Klebs-Loeffier bacillus, and diphtheria antitoxin protected against them. Schuetz (Berliner klin. Woch., Apr. 4, 11, and IS, '98).
With modification of .Neisser's stain by Concetti it is possible to arrive at a very early bacteriological diagnosis. The method is as follows: A sterilized glass or iron rod has twisted upon its end a small piece of absorbent cotton, impregnated with glucose glycerinated agar-agar. The rods are kept in steril ized test-tubes. When a culture is to be made, it is removed, the affected part swabbed with the end containing the culture-medium, and the rod at once re placed in the tube. It is then placed in a thermostat and kept at a temperature of 36° to 37° C. In four or five hours' time there will have been sufficient growth to make a smear. The latter is stained with a methylene-blue solution consisting of methylene-blue, 1 gramme; alcohol, 20 cubic centimetres; distilled water, 450 grammes; acetic acid, 5 grammes. This solution should remain on the slide not more than two or three seconds. The spread is then washed with water, after which it has an in tense-blue color. A counterstain is em ployed consisting of 2 grammes of vesu vin in 1000 grammes of water. This so lution is heated, and filtered while still warm. The specimen should be exposed to the action of the vesuvin from 15 to 20 seconds and then washed in water. It displaces the methylcne-blue. If no Loeffler bacilli are present, the gross appearance of the smear is brown. The presence of the true or pseudobacilli gives a mixed blue and brown color. Under the microscope the pscudobacilli are stained brown in their entirety. The true bacilli have a brown stain, but the ends of the bacilli present the char acteristic blue points, which is the chief differential test. A. L. Goodman (Med. Record, Feb. 16, 1901).