Latent tuberculosis infection among close contacts of multidrug-resistant tuberculosis patients in central Taiwan

SETTING: Both the tuberculin skin test (TST) and the QuantiFERON (R)-TB Gold In-Tube test (QFT-GIT) may be used to detect Mycobacterium tuberculosis infection. A positive reaction to either test can indicate latent tuberculosis infection (LTBI). These tests can be used to study the rate of infection in contacts of multidrug-resistant tuberculosis (MDR-TB) patients. OBJECTIVE: To evaluate the transmission status of MDR-TB patients in Taiwan by examining their close contacts and to compare the efficiency of TST and QFT-GIT. DESIGN: Chest radiographs, TST and QFT-GIT were performed in household contacts of confirmed MDR-TB patients to determine their infection status. RESULTS: A total of 78 close contacts of confirmed MDR-TB patients were included in the study. The majority of the MDR-TB patients were parents of the close contacts and lived in the same building; 46% of the subjects were TST-positive and 19% were QFT-GIT-positive, indicating LTBI that was likely to develop into active MDR-TB. There was a lack of consistency between TST and QFT-GIT results in subjects with previous bacille Calmette-Guerin vaccination. CONCLUSION: Household contacts of MDR-TB patients arc likely to develop LTBI; thus, follow-up and monitoring are mandatory to provide treatment and reduce the occurrence of active infection.