A case of Enterocytozoon bieneusi infection in an HIV-negative renal transplant recipient.

Reported here is a case of microsporidiosis that occurred in an HIV-negative renal transplant recipient. The patient developed protracted diarrhea 18 months following transplant surgery. Many spores of Enterocytozoon bieneusi were detected in stool smears using a modified trichrome staining method. Identification was confirmed using the polymerase chain reaction. Histological examination of duodenal biopsies revealed numerous spores in the cytoplasm of enterocytes. Tacrolimus and steroid regimens were decreased, treatment with mycophenolate mofetil was discontinued, and the patient was given albendazole and metronidazole for 2 weeks. The diarrhea resolved after 15 days of treatment; 2 months later the patient had recovered completely. A more systematic search for microsporidia using specific staining procedures should be performed in transplant recipients who develop severe diarrhea.