Abstract
In a previous report a thermolabile toxin component and thermostable tuberculin element were demonstrated in Berkfeld nitrates of broth cultures of tubercle bacilli.
The present investigation is an experimental clinical test of these observations in a preliminary series of 55 tuberculous patients, and groups of non-tuberculous patients and apparently normal persons as controls.
Berkfeld filtrates were prepared from 26-day-old broth cultures of a moderately virulent human strain of tubercle bacilli incubated at a temperature of from 37° to 39° C. One-tenth cubic centimeter of a 1:20 dilution of filtrate was injected intracutaneously on the anterior aspect of one forearm, and on the other the same dose of filtrate, previously heated at a temperature of 63° to 65° C. for one hour. Controls were made with equivalent amounts of the un-inoculated culture media.
Skin reactions were read after 24, 48 and 72 hours, and a note made of the time when the tests became entirely negative. Maximum reactions were observed uniformly after 48 hours, and usually showed definite infiltration and marked erythema at the sites of injection. Control material resulted negatively in all cases. Areas of reaction were approximated by measuring the extent of infiltration and reddening and recording the results in square centimeters.
The observations are summarized as follows:
The unheated Berkfeld filtrate gave the strongest and most persistent reactions as compared with those given by the heated material
Apparently normal persons, and those who1 had some clinical disease other than tuberculosis, gave sharp reactions of much longer duration and severity than did the tuberculous patients.
Tuberculous patients who could be classified as far advanced (50 cases) and relatively early pulmonary tuberculosis (5 cases) gave reactions which pointed to a clear-cut correlation between the type of skin reaction and the clinical course of the disease.
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