Diagnosis of infections caused by Enterocytozoon bieneusi and Encephalitozoon intestinalis using polymerase chain reaction in stool specimens

Objective: To study the usefulness of polymerase chain reaction (PCR) for the species identification of microsporidia in stool specimens obtained from HIV-infected patients with Enterocytozoon bieneusi or Encephalitozoon intestinalis infections. Setting: Infectious disease clinic in a university hospital. Patients: Thirty-seven stool specimens from 29 HIV-infected patients with microsporidiosis were tested. The diagnosis of microsporidian infection was made by light microscopy of stool specimens and species identification was made by transmission electron microscopy of duodenal biopsies. Sixty-one stool specimens from 45 HIV-infected patients without microsporidiosis sewed as controls. Methods: PCR was performed using DNA extracted from stools with two primers sets, one specific for E. bieneusi and one specific for E. intestinalis. Results: A 1265 base-pair fragment of the small subunit ribosomal RNA (rrs) gene could be amplified from all 31 stool specimens infected with E. bieneusi. In addition, a 930 base-pair fragment of the rrs gene could be amplified from all six stool specimens infected with E. intestinalis. The 61 control stools were negative with both primers. Conclusions: These results suggest that a PCR-based assay using species-specific primers sets can be used successfully for microsporidian species differentiation from stool specimens, thus obviating the need for invasive biopsy procedures.