BACKGROUND: Serial testing for tuberculosis (TB) exposure has been advocated among health care workers (HCWs) at risk of nosocomial infection.
OBJECTIVE: To determine the incidence and factors associated with TB infection among selected HCWs in Malaysia and to determine interferon-gamma response in serial testing.
DESIGN: A cohort of 769 HCWs were retested after 1 year using QuantiFERON®-TB Gold In-Tube. Incidence of TB infection was determined among HCWs who previously tested negative. Conversion and reversion rates using several definitions were explored.
RESULTS: Incidence of TB infection was 9.9 per 100 workers per year (95%CI 7.9-12.3). Working in the Emergency Department (ED; RR 2.18, 95%CI 1.07-4.43) was significantly associated with risk of TB infection. Reversion and conversion occurred frequently, with 46.7% reversion among HCWs with baseline interferon-gamma (IFN-γ) levels of 0.35-0.70 international units (IU)/ml, and 23.8% conversion among HCWs with baseline IFN-γ levels of 0.20-0.34 IU/ml.
CONCLUSIONS: TB infection control measures need to be strengthened, particularly in the ED, as the incidence of TB was high. Conversion and reversion rates in serial testing were high, and further studies are needed to facilitate its interpretation.
BACKGROUND: Health care workers are exposed to patients with tuberculosis and are at risk of nosocomial infection. The aim of this study was to determine the prevalence and factors associated with latent tuberculosis infection among health care workers in Malaysia and also to evaluate the agreement between Quantiferon TB Gold in tube test with Tuberculin Skin Test.
METHODS: A cross sectional study was conducted at four randomly selected hospitals in the Klang Valley from December 2008 to May 2009. Self administered questionnaire was used to obtain information on health care workers and possible risk factors. The response rate for this study was 90.8% with 954 respondents completed the questionnaire and were tested with Quantiferon TB Gold in tube for latent tuberculosis infection. Agreement between Quantiferon TB Gold in tube and Tuberculin Skin Test was assessed among 95 health care workers who consented to undergo both tests.
RESULTS: The overall prevalence of latent tuberculosis infection among health care workers was 10.6% (CI: 8.6%; 12.6%). Factors significantly associated with latent tuberculosis infection were aged 35 years and older [9.49 (CI: 2.22; 40.50)], history of living in the same house with close family members or friends who had active tuberculosis [8.69 (CI: 3.00; 25.18)], worked as a nurse [4.65 (CI: 1.10; 19.65)] and being male [3.70 (CI: 1.36; 10.02)]. Agreement between Quantiferon TB Gold in tube test and tuberculin skin test at cut-off points of 10 mm and 15 mm was 50.5% and 82.1% respectively. However, Kappa-agreement was poor for both cut-off points.
CONCLUSION: The prevalence of latent tuberculosis infection in Malaysia was relatively low for an intermediate TB burden country. We could not comment on the occupational risk of latent tuberculosis infection among health care worker compared to the general population as there were no prevalence data available for latent tuberculosis infection in the general population. Kappa agreement between Quantiferon TB gold in-tube and tuberculin skin test was poor.