MYCOBACTERIAL SKIN INFECTION IN ORGAN TRANSPLANT RECIPIENTS – EPIDEMIOLOGY, DIAGNOSIS, AND TREATMENT

Infections caused by mycobacteria occur not only in the early posttransplant period, during the time of the most intensive immunosuppression, but also in the late posttransplant period. They may be due to “typical” mycobacteria, M.tuberculosis, or atypical (or nontuberculous [NTM]) mycobacteria. Mycobacteria are acid-fast, nonmotile, weakly Gram-positive rods. NTM are ubiquitous environmental organisms with generally no attributable pathogenicity. Infection with M. tuberculosis, and in some cases with NTM, is not necessarily a sign of immunosuppression, but, particularly for NTM, depends on individual susceptibility. M.tuberculosis is acquired primarily by inhalation of aerosolized droplets containing the organisms, leading to an infection of the respiratory tract, with subsequent dissemination via the lymphatic system and the bloodstream. NTM comprise slow- and rapidly growing organisms, including M.marinum, M.kansasii, M.avium-intracellulare complex, M.xenopi, M.ulcerans (which causes Buruli ulcer, a chronic progressive disease and important health problem in West African countries), M.fortuitum, M.chelonae, and M.abscessus.

Epidemiology

There are very few epidemiological data on mycobacterial infections in solid organ transplant recipients. Infections with M.tuberculosis are uncommon in developed countries; however, these infections are increasing among foreign-born individuals in these countries. Mycobacterial infections seem to be rare in transplant patients, particularly in populations with a low prevalence of the disease. In developed Western countries the reported prevalence of tuberculosis in renal transplant recipients ranges from 0.35 to 4%. In developing countries the reported prevalence is much higher, occurring in up to 15% of transplant recipients in endemic areas.