[Screening of latent tuberculosis infection in health care workers by QuantiFERON-TB and tuberculin skin test]

Abstract

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 > or = 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.