Posttransplant Tuberculosis.

Tuberculosis is a major problem in the posttransplantation period, because of its high incidence and prevalence, difficulty in diagnosis as well as high risk of morbidity and mortality. In solid-organ transplant recipients, the diagnosis of tuberculosis is complex because it is paucisymptomatic. Tuberculin skin testing results may be negative, and interferon-gamma release assays may be insufficiently sensitive. Furthermore, imaging technique findings are mostly atypical, and sputum smear results can be negative despite the presence of active disease. Therefore, most tuberculosis cases are overlooked, and thus, treatment initiation is often delayed. The treatment of tuberculosis falls under 2 headings: that of active disease and latent disease. The drugs for treating these 2 entities are similar; however, their protocols are completely different. Active disease in the immunocompetent patient is treated mostly by giving isoniazid, rifampicin, pyrazinamide, and ethambutol for 2 months (intensive phase), followed by isoniazid and rifampicin for 4 months (continuation phase). The treatment of immunosuppressed patients is controversial; a similar protocol or longer duration of treatment has been suggested as compared to immunocompetent patients. Because there is a drug interaction between antituberculosis drugs (rifamycins) and immunosuppressants (calcineurin/mammalian target of rapamycin inhibitors and glucocorticoids), the risk of graft rejection increases during the treatment of tuberculosis. For the treatment of latent tuberculosis, in regions with a high prevalence of tuberculosis, universal prophylaxis with isoniazid for 6 months (preferably 9 months) has been recommended. In countries where the risk of tuberculosis is lower, no prophylaxis has been proposed. We propose that the best solution is to individualize therapy for patients at greatest risk of the disease. To conclude, posttransplant tuberculosis is still an important source of comorbidity in transplant recipients because of its high frequency, problems in diagnosis and treatment and association with increased risk of morbidity and mortality.