Polymerase chain reaction for microsporidian DNA in gastrointestinal biopsy specimens of HIV-infected patients

Objective: To study the accuracy of polymerase chain reaction (PCR) for microsporidian DNA in gastrointestinal biopsy specimens of HIV-infected patients for the diagnosis of intestinal microsporidiosis. Setting: infectious disease in- and outpatient clinic of a university hospital in Cologne, Germany. Patients: Forty-six HIV-infected patients with diarrhoea. Methods: PCR and Southern blot hybridization were performed using DNA extracted from intestinal biopsy specimens with primers and probes from the small subunit rRNA gene of Enterocytozoon bieneusi and Septata intestinalis. Histological examination of intestinal biopsy specimens was performed using a fluorescence technique. Transmission electron microscopy of intestinal biopsy specimens was performed in 13 patients. Results: Amplification and Southern blot hybridization with species-specific primers and probes gave positive results in 10 patients for E. bieneusi, and in 10 patients for S. intestinalis. Overall, five cases of double infection with E, bieneusi and S. intestinalis were seen when both primer pairs and probes were used. Histological examination showed microsporidian spores in all 15 cases, but light microscopy was unable to distinguish between species in almost all cases. Conclusions: PCR detection of microsporidian DNA in intestinal biopsy specimens can be used reliably for the diagnosis of intestinal microsporidiosis in HIV-infected patients and is also useful for species differentiation between microsporidia. Infections with S. intestinalis and double infections with two types of microsporidia appear to be more common than previously described.