Tuberculosis following kidney transplantation: report of paediatric case

Recipients of solid organ transplantation are, because of immunosuppressive therapy, at high risk to develop opportunistic infections including tuberculosis (TB). The incidence, clinical manifestations, and optimal diagnostic tests of this disease in this population have not been adequately defined. In this paper, we report a case of 13 year-old boy who developed pulmonary tuberculosis following a second renal transplantation from a deceased donor. The described case points diagnostic difficulties of the tuberculosis disease which are due to insidious and non specific clinical presentation. Also, the treatment is delicate because interaction between immunosuppressive drugs and antituberculosis drugs.


Introduction
It is well documented that immunosuppressive therapy exposes solid organ recipients to many serious complications including opportunistic infections [1]. In such immunocompromised patients, tuberculosis re-emerged as a serious complication frequently observed with atypical presentation causing delay in diagnosis [2].
The most of published cases were described in adult recipients from endemic area. In children tuberculosis has been rare and the few cases that have been reported [3]. We report here a rare case of pulmonary tuberculosis in a pediatric renal recipient with good outcome after conventional anti tuberculosis therapy.

Discussion
The incidence of tuberculosis after solid organ transplantation is higher compared with the general population [1][2][3]. The use of corticosteroids and immunosuppressive drugs interfere with T-cellmediated function, resulting in decreased host resistance to infection [4][5][6][7]. A longer duration of dialysis before transplantation, a previous history of infection, and a poor socioeconomic class are also reported as risk factors [7]. Tuberculosis generally occurs after 6 months of renal transplantation [5,6]. In our patient, TB was diagnosed early, three months after a second renal transplant.
There was no evidence of contact with individuals having active tuberculosis. The mode of contamination is probably a reactivation of latent infection or a transmission by the donor kidney. The clinical presentation of TB may be unusual and subtle in an immunosuppressed transplant recipient [5]. In every case of prolonged fever and unusual clinical manifestations, tuberculosis should be considered especially in endemic countries [5,7]. The Page number not for citation purposes 3 confirmation of mycobacterium tuberculosis infection is difficult.
Moreover, the bacteriologic culture may be negative and the tuberculin skin tests are often negative in the transplanted population [8]. In our patient, the search of mycobacterium tuberculosis by gastric tubing was negative but the diagnosis was made fortunately by the traditional tests: Zeihl-Neelsen staining and culture of sputum specimens aspirated during bronchoalveolar lavage. So, this diagnostic procedure should be considered in the diagnosis of pulmonary tuberculosis in children and adults. It allowed a better rate of diagnosis. New diagnostic tests have been developed recently to improve sensitivity and allow a rapid diagnosis of tuberculosis particularly in patients with culture-negative tuberculosis. The latest technique is especially the blood test measuring the Interferon-gamma released by stimulated T cells [8].
However, it should not be used in the first instance for diagnosis of active TB. Apart from the diagnostic difficulties, TB in transplant patients is a real therapeutic problem. Some authors reported an increased rate of acute rejection and a higher rate of graft loss because of interactions between CyA, prednisone and Rifampicin [5,6]. An adequate and regular monitoring of immunosuppressive drugs avoids the risk of rejection. The neurotoxicity of cyclosporine is well documented [7] and can be increased by INH; we then prescribe systematically pyridoxine to our patient. The prevention of TB is that difficult to achieve in solid organs transplanted patients.
The American Thoracic Society has recommended several years ago, a prophylactic INH administration to Mantoux-positive patients [8,9]. This strategy, however, is unlikely to be applicable in endemic areas, both because of a high degree of Mantoux positivity in the general population as well as the high frequency of false negative tests among chronic renal failure patients. Routine INH prophylaxis is therefore not recommended in endemic areas.

Conclusion
The clinical presentation of TB after renal transplantation may be different from that of the general population, which makes diagnosis a challenging task. The variety of immunosuppressive drugs which these patients receive and the consequent suppression of cellmediated immunity should theoretically place them at an increased risk for developing active tuberculosis. Multiple methods should be considered in the diagnostic approach to tuberculosis since none is totally efficient. Finally, the treatment of tuberculosis must take into consideration the drug toxicity and interactions.

Authors' contributions
All authors have read and agreed to the final version of this manuscript and have equally contributed to its content and to the management of the case.