Tuberculin skin testing in a hospital and two chronic care facilities in Prince Edward Island

To determine the prevalence of initial and booster positive responses to tuberculin skin testing among staff of an acute care hospital, and among staff and residents of two chronic care facilities on Prince Edward Island (PEI).

Two hundred and eighty-six staff from the hospital and the facilities, and 164 residents from the facilities were given tuberculin testing using 5 tuberculin units (TU) of purified protein derivative (PPD) of tuberculin. A two-step booster test was performed on 125 of 173 staff (73%) aged 35 years or older who initially tested negative, and on 138 of 141 residents (97.9%) at the chronic care homes.

The overall rate of initial tuberculin positivity among staff at the facilities was 15.7%. Among residents, the rate of positivity was 14.0%. Histories given by institutional staff of having previously received Bacille bilié de Calmette-Guérin vaccine (BCG) were associated with tuberculosis (TB) test reactivity, but not with mean reaction size. Staff with a history of BCG who tested positive did not differ in age from those testing negative. Institutional staff whose work involved patient contact were more likely to have a positive test than those whose work did not involve such contact. Booster positivity among those older than 35 years of age ranged from 2.0 to 5.2%.

These results suggest that, for health care institutions in PEI, tuberculin testing should be performed on all new or current hospital staff at risk of TB exposure, all new or current staff of chronic care facilities, and all new or current residents of chronic care facilities unless contraindicated. Booster testing should also be performed on all institutional staff and residents 35 years of age or older if their initial tuberculin test is negative.