"Efficacy and Safety of Levofloxacin vs Isoniazid in Latent Tuberculosis Infection in Liver Transplant Patients".

Inclusion Criteria: Liver transplantation candidates with age ≥ 18 years, no clinical or radiological evidence of active tuberculosis and negative pregnancy test (if applicable)who must meet one or more of the following criteria: * PPD skin test (initial or after a "booster effect") \>5 mm. Alternatively, the determination may be made by the interferon gamma (IFN-g) production in PPD-stimulated lymphocytes using the Quantiferon-TB or ELISPOT assays. * Past history of tuberculosis not properly treated. * Past history of contact with a patient with active TB. * Chest x-ray consistent with past untreated TB (apical fibronodular lesions, calcified solitary nodule, calcified lymph nodes or pleural thickening). The patient must give their written informed consent. Exclusion Criteria: * Lack of consent to participate in the study. * Intolerance or allergy to levofloxacin or to isoniazid. * Documented contact with tuberculosis resistant to levofloxacin or to isoniazid. * Treatment in the previous month with drugs with potential activity against Mycobacterium tuberculosis, (especially quinolones).