POSITIVE TUBERCULIN SKIN-TEST REACTIONS AMONG HOUSE STAFF AT A PUBLICHOSPITAL IN THE ERA OF RESURGENT TUBERCULOSIS

Background: The number and significance of tuberculin skin test reacti ons were compared with self-reported baseline values among house staff working in a public hospital. High-risk medical specialties, location s, and infection control practices were examined. Methods: House staff interviews, tuberculin skin test applications, review of employee hea lth service records, and environmental monitoring of high-risk areas w ere performed. Results: Among house staff self-reported as having nega tive tuberculin skin test status, 46.2% (95% CI 27.0% to 65.4%) of int ernal medicine house staff, compared with 4.8% (95% CI 4.3% to 13.9%) of house staff from other areas (p < 0.005), had positive results on a repeat tuberculin skin testing before graduation. These differences w ere not entirely explained by the use of surgical masks, year of train ing, or previous vaccination with bacille Calmette-Guerin. Most skin t est reactions (69%) occurred among house staff who had not been vaccin ated with bacille Calmette-Guerin. Increased skin reactivity probably represented excess conversions from unprotected exposure. Tuberculosis transmission was facilitated by delays in diagnosis, inadequate isola tion facilities, and suboptimal ventilation. House staff did not compl y with recommended tuberculosis surveillance because of time constrain ts, fear, and misunderstandings about tuberculin skin test interpretat ions in light of previous bacille Calmette-Guerin vaccination. Conclus ions: House staff in high-exposure settings with suboptimal environmen tal controls are at increased risk for tuberculosis infection. Partici pation in surveillance programs can be increased by enlisting the part icipation and advocacy of respected medical colleagues, screening hous e staff differentially according to exposure and job classifications, and more accurately interpreting subsequent test results from baseline two-step testing.