Posttransplant Mycobacterium Tuberculosis Disease Following Liver Transplantation and the Need for Cautious Evaluation of Quantiferon TB GOLD Results in the Transplant Setting: A Case Report M. Codeluppi, S. Cocchi, G. Guaraldi, F. Di Benedetto, N. De Ruvo, M. Meacci, B. Meccugni, R. Esposito, and G.E. Gerunda ABSTRACT This report describes a case of pulmonary tuberculosis in a liver transplant patient without a history of previous exposure to Mycobacterium tuberculosis (MTB) complex. Prior to transplantation, the tuberculin skin test was negative and the QuantiFERON–TB Gold (QFT Gold), an interferon gamma– based blood test, was negative before and after transplant including a period beginning on postoperative day 55 when the patient developed a febrile illness with an interstitial infiltrate and pleural effusion that was unresponsive to broad-spectrum antibiotic therapy. Empiric treatment with isoniazid, ethambutol, and levofloxacin resulted in resolution of the clinical symptoms. A sputum culture grew MTB on postoperative day 87. This case illustrates the need for caution when QFT Gold is used as diagnostic tool for latent tuberculosis during the pretransplant assessment. Further studies evaluating the usefulness of QFT Gold and other interferon gamma tests in posttransplantation active infection are warranted. D IAGNOSIS OF LATENT and active infection due to Mycobacterium tubercolosis (MTB) complex is diffi- cult to assess, both in patient candidates and recipients of liver transplantation, because of the frequent loss of tuber- culin skin test reactivity during end-stage liver disease and the atypical clinical presentations during active infections. 1 This justifies the attempt to use new diagnostic tests as an adjunctive tool confirm a diagnosis of latent or active MTB. QuantiFERON–TB Gold (QFT Gold) is an enzyme- linked immunosorbent assay that effectively evaluates the interferon gamma response to MTB-specific antigens early secreted antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10). The test has recently become com- mercially available. The test consists of a negative control (nil well, ie, whole blood without antigens or mitogen), a positive control (mito- gen well, ie, whole blood stimulated with the mitogen phyto- hemagglutinin [PHA]) and two sample wells (ie, whole blood stimulated with either ESAT-6 or CFP-10). The response to PHA is used as positive control, and the test is considered positive if the concentration of interferon gamma in the sample, after stimulation with ESAT-6 and CFP-10, is greater than or equal to 0.35 IU/mL (regardless of the result of the positive control). The result of the test is considered indeterminate if both antigen-stimulated samples are negative and if the value of the positive control is less than 0.5 IU/mL. 2 The concentration of interferon gamma is calculated after subtraction of the value of the nil well, which is considered the background. A negative response to PHA can reflect immune defects. In previous studies, QFT Gold and the tuberculin skin test (TST) showed variable agreement, and generally QFT Gold was found to be more sensitive for diagnosing latent infection 1 ; more recently, in one single-center study, the use of QFT Gold was found to be feasible in routine hospital use even though immunosuppression affects the test’s per- formance. 3 From the Department of Internal Medicine and Medical Spe- cialties (M.C., S.C., G.G., R.E.), Infectious Diseases Clinic, Uni- versity of Modena and Reggio Emilia, Modena, Italy; Microbio- logic and Virologic Laboratory Services (M.M., B.M.), Azienda Policlinico di Modena, Modena, Italy; and Division of Liver and Multivisceral Transplant Center (F.D.B., N.D.R., G.E.G.), Univer- sity of Modena and Reggio Emilia, Modena, Italy. Address reprint requests to Mauro Codeluppi, MD, Depart- ment of Internal Medicine and Medical Specialties, Infectious Diseases Clinic, University of Modena and Reggio Emilia School of Medicine, Via del Pozzo 71, 41100 Modena, Italy. E-mail: codeluppi.mauro@unimo.it © 2006 by Elsevier Inc. All rights reserved. 0041-1345/06/$–see front matter 360 Park Avenue South, New York, NY 10010-1710 doi:10.1016/j.transproceed.2006.02.012 Transplantation Proceedings, 38, 1083–1085 (2006) 1083