Comparison of Tuberculosis Exposure Frequency and Latent Tuberculosis Infection Rates Among Healthcare Workers by Occupational Classification

<b>Background:</b> The Korea Disease Control and Prevention Agency classifies healthcare workers (HCWs) into five groups based on <i>Mycobacterium tuberculosis</i> exposure risk and potential transmission impact to guide TB screening strategies. However, data on actual exposure frequency and latent tuberculosis infection (LTBI) incidence across these classifications remain limited. <b>Methods:</b> We conducted a retrospective cohort study of HCWs at a tertiary hospital between 2023 and 2024. Baseline LTBI screening was performed for all staff, with annual follow-up testing for Groups 1-4 according to national guidelines. TB exposure history and frequency were investigated and documented by the infection prevention department. LTBI incidence was assessed among HCWs with a negative test in 2023 who underwent repeat testing in 2024. <b>Results:</b> Among 2116 HCWs (27.7% male; mean age, 33 years), TB exposure rates increased with higher risk classification (Group 1: 46.9%, Group 2: 31.3%, Group 3: 18.5%, Group 4: 1.2%, Group 5: 0.6%; <i>p</i> < 0.001), as did the mean number of exposure events per person (1.39, 0.74, 0.31, 0.01, and 0.01, respectively; <i>p</i> < 0.001). The incidence of LTBI was 13/1323 (1.0%). After adjustment, LTBI incidence was associated with ≥2 TB exposure events (adjusted OR, 7.03; 95% CI, 1.87-26.36; <i>p</i> = 0.005), but did not differ significantly by group classification. <b>Conclusions:</b> This study suggests that occupational classification effectively predicts the frequency of TB exposure among healthcare workers. However, LTBI incidence is more closely associated with multiple TB exposure events rather than occupational classification.