[Tuberculin testing of hospital personnel: large investment with little impact]

Guidelines for the control and prevention of nosocomial tuberculosis include recommendations for surveillance of hospital employees with tuberculin skin 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 with 2000 employees and 21,000 admissions yearly. Tuberculosis cases among employees are reported for a 10-year period. TST were performed on engagement, if no recent positive result was available. A new TST was read in 717 (58%) of 1241 persons starting employment during the study period. In 261 workers in contact with 23 sputum smear positive 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 remaining 17 TST converters, 5 finally completed a full course of preventive chemotherapy. With a total workload of 547 hours for this result, half a year'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 TST 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.