Presentation by scanning electron microscopy of the life cycle of microsporidia of the genus Encephalitozoon.

This paper presents, for the first time, documentation by detailed scanning electron microscopy of the life cycle of microsporidia of the genus Encephalitozoon. Phase 1 is represented by the extracellular phase with mature spores liberated by the rupture of host cells. To infect new cells the spores have to discharge their polar filament. Spores with everted tubes show that these are helically coiled. When the polar tubules have started to penetrate into a host cell they are incomplete in length. The infection of a host cell can also be initiated by a phagocytic process of the extruded polar filament into an invagination channel of the host cell membrane. After the penetration process, the tube length is completed by polar tube protein which passes through the tube in the shape of swellings. A completely discharged polar tube with its tip is also shown. The end of a polar tube is normally hidden in the cytoplasm of the host cell. After completion of the tube length the transfer of the sporoplasm occurs and phase 2 starts. Phase 2 is the proliferative phase, or merogony, with the intracellular development of the parasite that cannot be documented by scanning electron microscopy. The subsequent intracellular phase 3, or sporogony, starts when the meronts transform into sporonts, documented as chain-like structures which subdivide into sporoblasts. The sporoblasts finally transform directly into spores which can be seen in their host cell, forming bubble-like swellings in the cell surface.

Prevalence and clinical significance of intestinal microsporidiosis in human immunodeficiency virus-infected patients with and without diarrhea in Germany: a prospective coprodiagnostic study.

The prevalence of intestinal microsporidiosis among human immunodefiency virus (HIV)-infected persons with chronic diarrhea varies from 7% to 50%; thus, microsporidia are a significant source of morbidity and, occasionally, mortality among these patients. Anecdotal reports suggest that intestinal microsporidiosis is also an important infection in patients with AIDS in Germany. To determine the prevalence of microsporidiosis among HIV-infected patients in Germany, we performed a prospective coprodiagnostic study of 97 consecutive HIV-infected patients. Microsporidia were the most common enteropathogen identified in 18 (36.0%) of 50 patients with diarrhea and 2 (4.3%) of 47 patients without diarrhea (P < .001; chi2 test). Microsporidia were present in 60% of patients with chronic diarrhea and 5.9% of patients with acute diarrhea. The etiologic agent was Enterocytozoon bieneusi in 18 patients and Encephalitozoon intestinalis in two patients. The prevalence of intestinal microsporidiosis in this cohort of German patients with AIDS and diarrhea is one of the highest to be reported anywhere in the world. Microsporidiosis seems to represent one of the most important causes of diarrhea in HIV-infected patients in Germany and thus must be considered in the differential diagnosis for all AIDS patients presenting with diarrhea.

Receptors for carbohydrate ligands including heparin on the cell surface of Leishmania and other trypanosomatids.

By employing neoglycoproteins (NGP) and glycosaminoglycans, the detection of endogenous glycoligand-binding sites has become possible. Monitoring specific binding of 11 of these sugar receptor-specific tools, 13 trypanosomatids of monogenetic genera Blastocrithidia, Crithidia, Herpetomonas, and Leptomonas and digenetic genera Endotrypanum, Leishmania, and Sauroleishmania were analysed by agglutination and fluorescence assays. NGP showed agglutination reactions only with the digenetic but not with the monogenetic species. Sensitive flow cytofluorimetric investigations revealed that the apparently different reactivity to NGP is due to a pronounced quantitative difference in expression of binding sites between mono- and digenetic flagellates. Moreover, flow cytofluorimetry was used to demonstrate the occurrence of receptor sites for heparin on the cell surfaces of all trypanosomatids. An indication for a correlation of the binding capacity for the NGP N-acetyl-beta-D-glucosamine and heparin to differences in the pathogenicity of parasites was observed for Leishmania donovani as well as Leishmania enriettii. Infective populations of these species contained a significantly higher number of cells which had bound N-acetyl-beta-D-glucosamine and heparin than noninfective (long-term in vitro-cultured) populations. The results of the present report additionally support the hypothesis that lectin-carbohydrate interactions with neutral sugar moieties and heparin or heparin-like molecules participate in the interactions between trypanosomatids and host (cells), and that the detected binding sites for carbohydrates and heparin may thus be referred to as potential virulence factors.

Species-specific identification of microsporidia in stool and intestinal biopsy specimens by the polymerase chain reaction.

In view of the increasing number of cases of human microsporidiosis, simple and rapid methods for clear identification of microsporidian parasites to the species level are required. In the present study, the polymerase chain reaction (PCR) was used for species-specific detection of Encephalitozoon cuniculi. Encephalitozoon hellem, Encephalitozoon (Septata) intestinalis, and Enterocytozoon bieneusi in both tissue and stool. Using stool specimens and intestinal biopsies of patients infected with Enterocytozoon bieneusi (n = 9), Encephalitozoon spp. (n = 2), and Encephalitozoon intestinalis (n = 1) as well as stool spiked with spores of Encephalitozoon cuniculi and Encephalitozoon hellem and tissue cultures of Encephalitozoon cuniculi and Encephalitozoon hellem, three procedures were developed to produce PCR-ready DNA directly from the samples. Specific detection of microsporidian pathogens was achieved in the first PCR. The subsequent nested PCR permitted species determination and verified the first PCR products. Without exception, the PCR assay confirmed electron microscopic detection of Enterocytozoon bieneusi and Encephalitozoon intestinalis in stool specimens and their corresponding biopsies and in spiked stool samples and tissue cultures infected with Encephalitozoon cuniculi and Encephalitozoon hellem. Moreover, identification of Encephalitozoon spp. could be specified as Encephalitozoon intestinalis. Whereas standard methods such as light and transmission electron microscopy may lack sensitivity or require more time and special equipment, the PCR procedure described facilitates species-specific identification of microsporidian parasites in stool, biopsies, and, probably, other samples in about five hours.