Old tuberculin and purified tuberculin: Standardization preparation of stable solutions

Abstract

In an attempt to simplify the Mantoux test, studies have been carried out in connection with the stability of the three dilutions of Old Tuberculin previously, employed for the Mantoux test. By diluting the tuberculin in a buffer solution pH 7·38, with the addition of 0·01 per cent quinosol, the dilution containing 1/100 mg. per 0·1 c.c. keeps well for about two months. Investigations were carried out into the serviceability of purified tuberculin (prepared on the principles of F. Seibert) in attempts to find two doses to replace the usual three doses of Old Tuberculin used for the complete Mantoux test. A description is given of the preparation of a purified tuberculin that dissolves as a clear solution in a buffer solution pH 7·38, with the addition of 0·01 per cent quinosol. In contrast to other preparations of purified tuberculin, including P.P.D., this solution gives no precipitate when quinosol is added as antiseptic. Standardization of purified tuberculin in relation to the international standard tuberculin is not practicable by means of the intracutaneous method usually employed. A comparison of the standard tuberculin with the purified tuberculin on the same principles followed by the American investigators has shown that for practical purposes it is safe to assume that: 1/100 mg. standard Old Tuberculin = 1/50000 mg. purified tuberculin 1/10 mg. standard Old Tuberculin = 1/5000 mg. purified tuberculin 1 mg. standard Old Tuberculin = 1/500 mg. purified tuberculin In Denmark it has proved practicable to use two doses of purified tuberculin for the performance of the Mantoux test, namely: 1/50000 mg. and 1/500 mg. Since 1935 these two doses of purified tuberculin have been employed in extensive serial examinations in various parts of this country, comprising about 10,000 examinations, without causing any particular inconvenience. These two doses together give approximately the same number of positive reactions as do the usual three doses of Old Tuberculin (1/100 mg., 1/10 mg. and 1 mg.). By using a third dose of purified tuberculin-namely, 1/50 mg. (corresponding to about 10 mg. of Old Tuberculin)—a few more positive reactions will be obtained (less than 5 per cent). For serial examinations and for work in tuberculosis clinics, where the use of two doses will greatly facilitate the rational performance of the Mantoux test, it may be considered sufficient to use only the doses 1/50000 mg. and 1/500 mg. As dilutions in a buffer solution pH 7·38 (with the addition of 0·01 per cent quinosol), containing 1/50000 mg. per 0·1 c.c., are stable for about one month, it is quite possible to prepare all the dilutions in a central institute and distribute them to hospitals and physicians ready for use. To supply the hospitals in Denmark with these solutions regularly once a month it is estimated that the yearly consumption of purified tuberculin will amount to something between one and two grams. This method therefore offers the following advantages: (1) It is quite inexpensive. (2) Uniform dilutions are distributed all over the country. (3) Mistakes in the preparation of tuberculin dilutions are avoided. Finally, a suggestion is made as to the preparation of an international standard purified tuberculin of the same strength as P.P.D. or the Danish preparation R.II. As we have made a preparation that is stronger than P.P.D., it will be necessary to standardize preparations of purified tuberculin in relation to the standard tuberculin, and to prepare the dilutions with a view to the strength thus assayed.