title: Evaluation of the tuberculin skin test and the interferon-gamma release assay for TB screening in French healthcare workers.
abstract: BACKGROUND
  Using French cut-offs for the Tuberculin Skin Test (TST), results of the TST were compared with the results of an Interferon-gamma Release Assay (IGRA) in Healthcare Workers (HCW) after contact to AFB-positive TB patients.
  
  
  METHODS
  Between May 2006 and May 2007, a total of 148 HCWs of the University Hospital in Nantes, France were tested simultaneously with IGRA und TST. A TST was considered to indicate recent latent TB infection (LTBI) if an increase of >10 mm or if TST >/= 15 mm for those with no previous TST result was observed. For those with a positive TST, chest X-ray was performed and preventive chemotherapy was offered.
  
  
  RESULTS
  All HCWs were BCG-vaccinated. The IGRA was positive in 18.9% and TST >/= 10 mm was observed in 65.5%. A recent LTBI was believed to be highly probable in 30.4% following TST. Agreement between IGRA and TST was low (kappa 0.041). In 10 (16.7%) out of 60 HCWs who needed chest X-ray following TST the IGRA was positive. In 9 (20%) out of 45 HCWs to whom preventive chemotherapy was offered following TST the IGRA was positive. Of those considered TST-negative following the French guidelines, 20.5% were IGRA-positive. In a two-step strategy - positive TST verified by IGRA - 18 out of 28 (64.3%) IGRA-positive HCWs would not have been detected using French guidelines for TST interpretation.
  
  
  CONCLUSIONS
  The introduction of IGRA in contact tracings of BCG-vaccinated HCWs reduces X-rays and preventive chemotherapies. Increasing the cut-off for a positive TST does not seem to be helpful to overcome the effect of BCG vaccination on TST.
authors: Department of Occupational Medicine and Occupational Hazards, University Hospital of Nantes, France. Dominique.Tripodi@chu-nantes.fr.
authors: Dominique
authors: D
authors: Tripodi
authors: Benedicte
authors: B
authors: Brunet-Courtois
authors: Virginie
authors: V
authors: Nael
authors: Marie
authors: M
authors: Audrain
authors: Edmond
authors: E
authors: Chailleux
authors: Patrick
authors: P
authors: Germaud
authors: Frederique
authors: F
authors: Naudin
authors: Jean-Yves
authors: JY
authors: Muller
authors: Martine
authors: M
authors: Bourrut-Lacouture
authors: Marie-Henriette
authors: MH
authors: Durand-Perdriel
authors: Claire
authors: C
authors: Gordeeff
authors: Guyonne
authors: G
authors: Guillaumin
authors: Marietherese
authors: M
authors: Houdebine
authors: Francois
authors: F
authors: Raffi
authors: David
authors: D
authors: Boutoille
authors: Charlotte
authors: C
authors: Biron
authors: Gilles
authors: G
authors: Potel
authors: Claude
authors: C
authors: Roedlich
authors: Christian
authors: C
authors: Geraut
authors: Anja
authors: A
authors: Schablon
authors: Albert
authors: A
authors: Nienhaus