Introduction: Tuberculosis (TB) presents globally as a significant health problem and health care workers (HCW) are at increased risk of contracting TB infection. There is no diagnostic gold standard for latent TB infection (LTBI). Tuberculin Skin Test (TST) is the traditional testing method for diagnosing LTBI, but it has a known high rate of false positive with subsequent needless loss of time, efforts, loss of productivity and side effects. Quantiferon test (QFT) has been developed as a potential replacement for the TST. Aim of work: To assess the prevalence of TB among health care workers in high, medium and low risk areas for TB infection at Cairo University Hospitals (CUH) and to validate the use of Quantiferon as a screening test for TB compared to tuberculin test. Materials and Methods: A cross sectional study with convenient sample of 200 HCWs employed in Cairo University Hospitals and agreed to participate was performed. Information on gender, age, workplace, job title, BCG vaccination and history of both TB and TST were collected using a questionnaire. All participants were subjected to clinical examination, TST, Quantiferon test and chest X-ray. Results: The participants were 70 males and 130 females with mean age + SD (34.7 ± 12.6years). TST was positive in 86 cases (43%) and the QFT results were positive in 38 cases (19%). There was average agreement between the two tests (76%, к = 0.474), concordance between two tests improved from (к = 0.474) at cut-off point 10 mm to (к = 0.492) at cut-off point 15 mm. LTBI was most common principally among nurses, workers in Chest Department, Internal Medicine Department and technicians in bacteriology lab with highest mean diameter of induration for the studied population in the chest department (16.6mm). According to the nature of work the laboratory technicians had the highest mean diameter of induration (16.58mm). Thirty-four (17%) of the studied 
population had abnormal chest radiographs suspected of TB. Occupational exposure in high risk area and working duration >10 years were statistically significant risk factors for both QFT & TST, while age and nature of work were not statistically significant risk factors for both tests using multivariable logistic regression. Conclusion and Recommendations: There is risk of tuberculosis transmission among HCWs at Cairo University Hospitals, principally among nurses, workers in Chest Department, Internal Medicine Department and technicians in bacteriology lab. Large scale of screening involving all University hospitals staff must be performed.
We recommend screening of HCWs using TST then confirming positive cases by Quantiferon and following them. Disease probability in HCWs tested positive by serial testing should be further assessed by chest radiograph. Further reinforcement of the infection control policy is a must and treatment regimen for latent TB infection has to be followed.