The Dick test in scarlet fever / by C.C. Okell and H.J. Parish.

  • Okell, C. C. (Charles Cyril), 1888-1939.
Date:
1925?]
Catalogue details

Licence: In copyright

Credit: The Dick test in scarlet fever / by C.C. Okell and H.J. Parish. Source: Wellcome Collection.

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    7 R f&io Reprinted from The Lancet, April 4th, 1925, p. 712. — THE DICK TEST IK SCARLET FEVER. By C. C. OKELL, M.C., M.B., M.R.C.P. Lond., AND H. J. PARISH, M.D., M.R.C.P. Edin. (From the Wellcome Physiological Research Laboratories.) The small number of observations on the Dick test so far published in Europe encourages us to bring forward the following results. In July last, Okell and Baxter 1 reported the results of a number of tests. Ker, McCartney and McGarrity 2 (1925) have reported a further series. The present communication describes a further series of tests done on scarlet fever patients and on normal individuals. The Toxin. The toxin used in all these tests was prepared by us from a strain of streptococcus kindly sent to us by Dr. Dochez. It consisted of a filtrate of a 16-hour- old culture of the streptococcus in Douglas’s 3 trypsin digest medium as modified by Hartley 4 and subse¬ quently by Watson and Wallace.5 An intradermal injection of 0-2 c.cm. of a 1/6000 dilution of the toxin was found to give a well-marked reaction 20 to 70 mm. in diameter in susceptible persons, the average positive reaction being about 20 X 30 mm. Dick toxin is much more heat stable than diphtheria toxin, and is practically unaffected by heating to 75° C. for ten minutes, a procedure which always inactivates dilutions of diphtheria toxin. The method employed for the inactivation of the toxin for the control inoculation is heating to 96° C. for 45 minutes. The constituent responsible for the pseudo reaction seems to be very little affected by this treatment. The toxin keeps for at least two weeks in the diluted state, and phenol (e.g., 0-4 per cent.) may be used as a preserva¬ tive in the dilutions. Dick toxin, unlike diphtheria toxin, does not appear to produce tissue necrosis. Dick and Dick6 and others report that many reacting doses can be given without causing any permanent tissue damage. In the dilutions employed in the test it appears to have a vaso-dilator effect on the capillaries. We have prepared toxins not only from Dochez’s strain but from strains sent us by Dr. Dick of Chicago and Dr. W. II. Park of New York, as well as from two strains isolated in London by ourselves. All these toxigenic strains appeared to fall into one