title: Determining the Latent Tuberculosis Infection by IFN - γ Elispot Assay in Healthcare Workers From University Hospitals of Shiraz, South West of Iran.
abstract: BACKGROUND
  Classical screening methods are incapable to properly detect LTBI (Latent TB Infection) and HCWs (Healthcare Workers) are at the high risk of exposure. Only few reports estimated the prevalence of LTBI among Iranian HCWs and they mostly used the TST (Tuberculin Skin Test), rather than assessing the response against TB-specific antigens.
  
  
  OBJECTIVE
  The current study aimed to determine the frequency of IFN - γ producing blood cells of microbiology and radiology ward technicians by an in-house IFN - γ ELISPOT assay in the University hospitals of Shiraz University of Medical Sciences (SUMS) against recombinant ESAT - 6 and PPD antigens.
  
  
  METHODS
  89 HCWs from medical laboratory and radiology departments of Shiraz University of Medical Sciences' hospitals, South of Iran, were screened for LTBI. To achieve the goal, an in-house IFN - γ (Interferon - gamma) ELISPOT (Enzyme Linked ImmunoSpot) assay was used to detect the reactivity against ESAT - 6 (Early Secreted Antigen Target protein - 6) and the PPD (Purified Protein Derivate).
  
  
  RESULTS
  Almost 8% of the personnel showed positive TST (over 10 mm) reaction while 29% of them had considerable T - cell reactivity against PPD in ELISPOT assays. However, the ESAT - 6 reactivity was found only in one case of HCWs. No correlation was found between the patterns of the reactions and the age or the duration of the employment or previous vaccination history of the participants. The ELISPOT results were not correlated with the TST results.
  
  
  CONCLUSIONS
  Considering the hindrance of TST, the IFN - γ ESAT - 6 ELISPOT assay, even in forms of in-house tests, could replace traditional methods to properly spot the LTBI among the high risk groups from Iran's health system.
authors.affiliation: Department of Microbiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taheri
authors.affiliation: Immunotherapy laboratory, Department of Immunology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Bazrafkan
authors.affiliation: Immunotherapy laboratory, Department of Immunology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Habibagahi
keywords: Enzyme-Linked Immunospot Assay; Interferon - gamma; Iran; Latent tuberculosis; Tuberculin test