Follow-Up Study of Tuberculosis-Exposed Supermarket Customers with Negative Tuberculin Skin Test Results in Association with Positive Gamma Interferon Release Assay Results

We report a follow-up study of 29 subjects with negative tuberculin skin test (TST) results in association with positive gamma interferon release assay (IGRA) results, mainly due to responses to CFP-10 in the T-SPOT.TB assay, during a contact investigation. One year later, 12/29 subjects (41%) had converted to positive TST results in association with negative IGRA results.