Two-step tuberculin testing and BCG vaccination in the personnel of a medical and pharmaceutical university

Abstract

In an attempt to cope with recent nosocomial spread of tuberculosis, the tuberculin test with a 0.05 microgram of 0.1 ml intradermal dose of purified protein derivative was performed by a two-step procedure on the personnel of a medical and pharmaceutical university, followed by BCG vaccination for non-reactors in the second test. The second test was repeated after two weeks in all but those with erythema of 10 mm or more in diameter associated with double erythema, vesicle formation, and/or necrosis on the initial testing. The first test was done in a total of 935 participants (73% of all personnel) with a median age of 37 (range, 21-67) years. The rate of participation, by occupation, in the hospital personnel ranged from 63% (183/289) for doctors to 98% (351/358) for nurses. The size of erythema showed a unimodal distribution with a peak in the range of 10-19 mm, with a median of 20 mm (range, 0-102). Reactions below 9 mm, which are interpreted as negative, were found in 16% of all participants, and those above 30 mm in 35%. Among participants aged 20-49 years, especially among nurses, reactions tended to be larger with increasing age. Among 539 participants undergoing repeated testing, reactions between the first and second tests correlated well, showing a median increase in size of 10 mm (range, -43-(+)70) on retesting. Reactions above 30 mm associated with an increase in size larger than 20 mm, among those initially below 29 mm in diameter, were observed in 28% of those retested. Adverse reactions such as vesicle formation with or without hemorrhage, or lymphangitis occurred in 2.5% of all participants on the initial testing and in 1.5% on the retesting, with the highest frequency seen in those aged 30-39 years. BCG was administered to 26 of the 49 participants with a negative reaction on the second test. All vaccinees with a median age of 30 (range, 21-46) years showed tuberculin conversion after two months without developing Koch's phenomenon soon after the vaccination. Incidentally, it is desirable that two-step tuberculin testing such as that in the present study should also be performed using the diameter of induration, particularly that measured transversely, since erythema is not used in any other country than Japan.