[Two-step tuberculin skin test in general hospital workers--comparison with nursing home workers]

In 1998, the Japanese Society for Tuberculosis recommended two-step tuberculin skin test (TST) for medical workers. As a large majority of the Japanese were BCG vaccinated in their childhood, it is difficult to distinguish true infection from booster effect. In Japan, it is important to record individual baseline tuberculin reactivity by two-step TST. Two-step TST was performed on 126 general hospital workers and 47 nursing home workers, excluding those whose initial TST was strongly positive, according to the recommendation of the Japanese Society for Tuberculosis in 1998 (strongly positive TST in Japan is defined as the reaction with other intensive responses such as double skin erythema, bleb, lymphangitis, etc.). Diameter of erythema of TST among hospital workers v.s. nursing home workers were as follows. In the initial TST: 23.2 +/- 16.7 mm v.s. 14.2 +/- 10.3 mm (p < 0.001), in the second TST: 26.3 +/- 17.1 mm v.s. 16.7 +/- 9.9 mm (p < 0.02), baseline of TST: 32.0 +/- 18.3 mm v.s. 19.4 +/- 10.7 mm (p < 0.001). Booster effect of TST in hospital workers was +9.8 +/- 15.1 mm, while it was +4.8 +/- 7.8 mm (not significant) in nursing home workers. Among those 30 years and over, these differences were no found, except diameter of erythema in the initial TST. In our hospital with no beds for TB, in the past 10 years, tuberculosis has not been broken out among our hospital workers, while several patients with pulmonary tuberculosis have been diagnosed every year (6 patients in 1999). Thus, some hospital workers might be exposed to infection with tuberculosis from these patients. On the other hands, no tuberculosis patients had been diagnosed in the nursing home, and young nursing home workers very rarely exposed to infection with tuberculosis in their life, and they are similar to the general population. This study suggested that hospital workers were more frequently exposed to tuberculosis infection than other workers.