Tuberculin skin testing of hospital employees: big workload with little impact

Guidelines for the control and prevention of nosocomial tuberculosis includ e recommendations for surveillance of hospital employees with tuberculin sk in tests (TST). We analysed a 2 1/2-year period of tuberculin skin testing at Kantonsspital St. Gallen, an 850-bed hospital in eastern Switzerland wit h 2000 employees and 21000 admissions yearly. Tuberculosis cases among empl oyees are reported for a 10-year period. TST were performed on engagement, if no recent positive result was availabl e. A new TST was read in 717 (58%) of 1241 persons starting employment duri ng the study period. In 261 workers in contact with 23 sputum smear positiv e tuberculosis patients, 180 (69%) follow-up TST were performed. Of a total of 37 increases in TST, 20 (54%) were retrospectively-attributed to other causes than a recent infection with M. tuberculosis (vaccination with BCG, booster phenomenon, doubts concerning the previous test result). Of the rem aining 17 TST converters, 5 finally completed a full course of preventive c hemotherapy. With a total workload of 547 hours for this result, half a yea r's working hours were necessary to prevent one case of active tuberculosis . Over a 10-year period, 4 out of 9 active tuberculosis cases in employees were likely to be nosocomially acquired, but none was diagnosed thanks to T ST surveillance. We conclude that surveillance with TST is time consuming, but has little impact on the tuberculosis situation in hospital employees. Alternative strategies to this unsatisfactory system are discussed.