Estimating the prevalence of tuberculosis infection among healthcare workers in our hospital by repeat QFT-G testing]

The QuantiFERON-TB (QFT) blood test is the major tool for the diagnosis of Mycobacterium tuberculosis (TB) infection among healthcare workers (HCWs). We used QFT tests to estimate the prevalence of TB infection among HCWs in our hospital.Between 2003 and 2010, a total of 733 HCWs were enrolled in this study, and the prevalence of TB infection was analyzed according to the HCWs' jobs and work place.Among the 152 men and 581 women who were evaluated, 3 female HCWs had a history of TB. Fifty-eight HCWs (8 men and 50 women with a mean age of 56.3 years and 48.4 years, respectively) demonstrated positive QFT tests. The positive rate was 7.9% for all staff members throughout the study period. The QFT test was positive for 1 HCW who was treated for TB in 1998, and negative and inconclusive for 2 other HCWs treated for TB in 2002. The positive rate for QFT was 16.0% in the TB ward (12/75, 95% confidence interval [CI]: 7.7-24.3%), 9.9% in the other wards (22/222, 95% CI: 7.9-11.9), and 1.1% in the outpatient department (1/91, 95% CI: 0-2.2). According to the job category, the QFT positive rates were as follows: doctors, 4.3% (3/70, 95% CI: 1.9-6.7); nurses, 10.3 (4/35, 95% CI: 6.0-16.8). The positive rate among doctors working in the TB ward was 10.0%, and that for nurses was 24.3%. This indicates that the prevalence of infection among HCWs in the TB ward was significantly higher than that in other work places. A comparison of the results from 2003 through 2007 revealed that for a total of 307 workers, 90.6% and 5.2% remained negative and positive, respectively, while 1.6% converted from negative to positive, and 2.6% from positive to negative.The positive rate among HCWs in the TB ward was higher than that in other wards. This is especially remarkable for doctors and nurses working in the TB ward.