Diagnosis of Tuberculosis Infection in Health Care Workers Using Ex-vivo Interferon-gamma Assay

其他：new healthcare workers

doctors and nurses who were newly hired in 2008 at the Samsung Medical Center

其他：1-step tuberculin skin test (TST) and blood sampling

In only new healthcare workers, the 1-step TST and quantiFERON-TB Gold In-Tube test were performed.

Annual Incidence of Tuberculosis Infection Among Newly Employed Doctors and Nurses in Korea

The participants performed QuaniFERON-TB Gold In-Tube test (QFT-IT test). Annual infection of tuberculosis infection was evaluated with the conversion of QFT-IT test through annual check up of QFT-IT test. The definitions for QFT-IT test conversion was based on the CDC definition (Baseline IFN-r < 0.35 IU/ml and follow-up IFN-r ≥ 0.35 IU/ml).

Negative Conversion Rate in Follow-up QuantiFERON-TB Gold In-Tube Test (QFT-IT Test) After Treatment of Latent Tuberculosis Infection (LTBI)

The percentage of participants with negative conversion in follow-up QFT-IT test after LTBI treatment, out of those who had QFT-IT test conversion after one year of employment and agreed to undergo treatment for LTBI according to our recommendation

Participants with QFT-IT test conversion were recommended for LTBI therapy using 3 months of daily isoniazid and rifampicin, which was the regular treatment for LTBI in our institution.

The QFT-IT test was repeated after LTBI therapy. Negative conversion was defined as baseline IFN-r ≥ 0.35 and follow-up IFN-r < 0.35 IU/ml.