Tuberculosis skin test conversion among health care workers at a military medical center

Health care workers (HCW) are at risk of occupationally acquiring Mycobacterium tuberculosis (TB) infection. The Centers for Disease Control and Prevention has published guidelines for health care facilities to protect HCW. One of the recommended elements is TB infection surveillance among HCW using purified protein derivative (PPD) skin testing and analysis of the data by occupational group and work location to determine areas of increased risk of infection. At the military medical center (MMC) we studied, occupational groups with statistically significant (p < 0.05) above-average PPD conversion risk (> 1.1%/year) included respiratory therapists (15.6%/year), nursing technicians (2.3%/year), and military personnel (1.6%/year). Maintenance and engineering workers (2.6%/year), food service workers (2.5%/year), laboratory workers (2.0%/year), custodial workers (1.8%/year), and practical nurses (1.7%/year) had above-average, but not statistically significant, risk. The fourth floor of the MMC had 39% (21/54) of the converters. The surveillance program also uncovered 235 individuals who had not completed adequate prophylactic therapy, and a case of active TB in a laboratory worker.