Screening dell’infezione tubercolare latente in operatori sanitari con QuantiFERON-TB e test cutaneo tubercolinico [Screening of latent tuberculosis infection in health care workers by QuantiFERON-TB and tuberculin skin test]

Background. Recent guidelines (MMWR 2005) recommend the use of QuantiFERON-TB (QFT-TB) as an alternative to the tuberculin skin test (TST) for the screening of latent tuberculosis infection (LTBI) in health care workers (HCWs). Materials and methods. 590 HCWs were screened for LTBI by TST and QFT-TB. Results were compared with risk factors for LTBI, determined by questionnaires. Results. Both tests were significantly associated with non-Italian nationality [TCT (OR=9.17), QFT-TB (OR=3.65)], age ≥ 45 years old [TCT (OR=1.81), QFT-TB (OR=2.36)], history of household contacts [TCT (OR=2.65), QFT-TB (OR=3.37], occupational exposure to tuberculosis (TB) patients [TCT (OR=2.14), QFT-TB (OR=1.93)]. 55 cases were discordant (28 QFT-TB-negatives/TCT-positives; 27 QFT-TB-positives/TCT-negatives). Both tests were not associated with workplace risk factors or TB risk level assessed in different hospital units. Conclusions. In HCWs employed in a low TB incidence area both QFT-TB and TCT were more associated with non occupational risk factors (nationality, age, household contacts) than with main determinants of workplace risk for LTBI.