Microsporidiosis in the graft of a renal transplant recipient.

Microsporidia are intracellular protozoa that are emerging as significant opportunistic infections in AIDS patients. Although there are numerous published reports of intestinal and disseminated infections in patients with AIDS, there have been only two previous reports in transplantation medicine, both on intestinal microsporidiosis. We report here the first documented case of extra-intestinal microsporidiosis in a transplant recipient. A 39-year-old renal transplant recipient presented with a pyrexia and deteriorating graft function. Light microscopic examination of a renal allograft biopsy revealed numerous microsporidian spores within the renal tubular epithelium. Transmission electron microscopy confirmed the presence of an Encephalitozoon infection and was highly suggestive of Encephalitozoon intestinalis. Therapy with albendazole was extremely effective and resulted in recovery of renal function. Although a rare cause of renal allograft dysfunction, microsporidiosis is curable. It may be underdiagnosed, and should be considered in the differential diagnosis of transplant recipients presenting with opportunistic infections.