Dual infection of urinary tract with Enterocytozoon bieneusi and Encephalitozoon cuniculi in HIV/AIDS patients

Microsporidia are emerging pathogens which cause an opportunistic infections in immunocompromised patients, especially those with AIDS. Intestinal microsporidiosis is the most recognized infection, whereas urinary tract infections caused by microsporidia are rarely paid attention to either due to their subclinical course or diagnostic difficulties. In this report dual microsporidial infection of urinary tract, caused by Enterocytozoon bieneusi and Encephalitozoon cuniculi was described in HIV/AIDS patients under cART therapy. Since microsporidiosis can cause severe complications or even death in immunosuppressed patients, our results suggest that microsporidial infection should be included in routine investigation of HIV-positive patients, even asymptomatic.

Diabetes mellitus increases the susceptibility to encephalitozoonosis in mice

Microsporidiosis are diseases caused by opportunistic intracellular fungi in immunosuppressed individuals, as well as in transplanted patients, the elderly and children, among others. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and decreased T cell response, neutrophil function, humoral immunity failure, increasing the susceptibility to infections. Here, we investigated the susceptibility of streptozotocin (STZ)-induced type I diabetic and/or immunosuppressed mice to encephalitozoonosis by Encephalitozoon cuniculi. Microscopically, granulomatous hepatitis, interstitial pneumonia and pielonephritis were observed in all infected groups. STZ treatment induced an immunossupressor effect in the populations of B (B-1 and B2) and CD4⁺ T lymphocytes. Moreover, infection decreased CD4⁺ and CD8⁺ T lymphocytes and macrophages of DM mice. Furthermore, infection induced a significant increase of IL-6 and TNF-α cytokine serum levels in DM mice. IFN-γ, the most important cytokine for the resolution of encephalitozoonosis, increased only in infected mice. In addition to the decreased immune response, DM mice were more susceptible to encephalitozoonosis, associated with increased fungal burden, and symptoms. Additionally, cyclophosphamide immunosuppression in DM mice further increased the susceptibility to encephalitozoonosis. Thus, microsporidiosis should be considered in the differential diagnosis of comorbidities in diabetics.

Radiographic signs of renal disease in rabbits

The radiological features of 65 rabbits with suspected renal disease are reviewed. The radiological features included a generalised increase in bone opacity (osteosclerosis), renomegaly, nephroliths, ureteroliths and soft tissue mineralisation. One or more of these changes were present on radiographs of 57 of the 65 rabbits. Renal disease was suspected because of the clinical signs and the presence of kidney stones and/or high blood concentrations of urea and creatinine. Significant renal disease was confirmed in 14 cases that were examined postmortem. Blood urea and creatinine concentrations were measured in 47 cases but not all the rabbits had high levels of both. Blood calcium concentration was high in 33 of the 38 rabbits in which it was measured. Serum phosphate was high in 17 and low in five of 34 rabbits in which it was measured. Hyperphosphataemia was associated with generalised osteosclerosis and aortic calcification. Rabbits with osteosclerosis were thin, depressed and unwilling to move. Thirty-eight of 41 rabbits that were tested were seropositive for antibodies to Encephalitozoon cuniculi. Histological lesions suggestive of E cuniculi infection were found in all 13 cases that were examined postmortem, although the organisms were visible in only one case.

Encephalitozoon cuniculi placentitis and abortion in a quarterhorse mare

Encephalitozoon cuniculi is a microsporidial parasite, which has rarely been reported to cause placentitis in animals. A late-term aborted fetus and placenta from a Quarterhorse were presented to the Livestock Disease Diagnostic Center, University of Kentucky, for diagnostic examination. There was a necrotizing placentitis, with distension of many chorionic epithelial cells by intracytoplasmic vacuoles containing 1-2-microm-diameter, elongated, gram-positive organisms. The organisms were identified as E. cuniculi by electron microscopy and by polymerase chain reaction using primers to microsporidial ribosomal DNA. Joints of the fetus were swollen, with gross and microscopic lesions of synovitis; however, E. cuniculi DNA was not detected.

Phacoemulsification for the management of Encephalitozoon cuniculi-induced phacoclastic uveitis in a rabbit

Phacoemulsification was performed on a New Zealand White rabbit with slowly progressive unilateral phacoclastic uveitis and cataract formation. The irrigating solution with lenticular contents were centrifuged and examined cytologically using Weber's chromotrope-based stain. Microsporidial spores were observed and positively identified as Encephalitozoon cuniculi via polymerase chain reaction. More than 1 year following surgical therapy, the rabbit is visual and comfortable without medications.

Disseminated microsporidiosis caused by Encephalitozoon cuniculi III (dog type) in an Italian AIDS patient: a retrospective study

We report a case of disseminated microsporidiosis in an Italian woman with AIDS. This study was done retrospectively using formalin-fixed, paraffin-embedded tissue specimens obtained at autopsy. Microsporidia spores were found in the necrotic lesions of the liver, kidney, and adrenal gland and in ovary, brain, heart, spleen, lung, and lymph nodes. The infecting agent was identified as belonging to the genus Encephalitozoon based on transmission electron microscopy and indirect immunofluorescence. Additional molecular studies, including sequence of the rDNA internal transcribed spacer region, identified the agent as E. cuniculi, Genotype III. We believe that this is the first report of a human case of disseminated microsporidial infection involving the ovary.

Dual microsporidial infection with Encephalitozoon cuniculi and Enterocytozoon bieneusi in an HIV-positive patient

This report describes the first dual microsporidial infection with Encephalitozoon cuniculi and Enterocytozoon bieneusi in an HIV-positive patient. In view of clinical and epidemiological findings, our E. cuniculi isolate was deduced to be of the dog strain. The patient's occupational involvement with dogs indicates that canines should be considered as a reservoir of human infections for both microsporidial species. Furthermore, our report provides detailed clinical and radiological information on a rare case of a symptomatic pulmonary infection by E. cuniculi and its improvement after treatment with albendazole.

[Generalized microsporidiosis caused by Encephalitozoon sp. in a pediatric patient with Bruton's disease]

We present the case of a four-year-old boy with a history of repeated upper respiratory tract infections and pyoderma. He presented fever, seizures, inability to talk, loss of swallowing, fine tremor in the upper extremities; positive bilateral Babinski reflex and quadriparesis. The diagnosis of Bruton's disease and generalized microporidiosis was based on immunologic analysis, smear tests with chromotrope R2 stain and indirect immunofluorescense with monoclonal 3B6 antibody for Encephalitozoon species in samples of spinal fluid, bronchial and paranasal sinus aspirates and stool, which were all positive. The patient was treated with albendazol during 72 days; he left the hospital in a good condition, walking, talking and able to swallow. His laboratory test controls were negative; he is followed up in the outpatient department.

Disseminated infection due to Encephalitozoon cuniculi in a patient with AIDS: case report and review

OBJECTIVE AND METHODS

Infections due to microsporidia are increasingly recognized as opportunistic infections in patients with AIDS. We describe here a case of disseminated infection due to Encephalitozoon cuniculi and review the literature on this microsporidial infection.

RESULTS

All 12 patients reported in the literature had AIDS and nine presented with disseminated infection involving the kidneys, sinuses, lungs, brain and conjunctiva. Asymptomatic infection was seen in three patients. Microsporidia were detected by light microscopy examination of urine samples in all the cases. Species identification was performed by various genotypic methods or transmission electron microscopy. Eight of 12 patients who received albendazole therapy experienced clinical improvement with documented clearance of spores in five of these eight patients. Two patients relapsed.

CONCLUSIONS

E. cuniculi infection should be considered in severely immunocompromised HIV-infected patients with multi-organ involvement and fever, especially when renal failure is present. Microsporidial spores are usually seen in urine samples and in the involved organ. Albendazole therapy seems to be effective.

Microsporidia: emerging advances in understanding the basic biology of these unique organisms

Microsporidia are long-known parasites of a wide variety of invertebrate and vertebrate hosts. The emergence of these obligate intracellular organisms as important opportunistic pathogens during the AIDS pandemic and the discovery of new species in humans renewed interest in this unique group of organisms. This review summarises recent advances in the field of molecular biology of microsporidia which (i) contributed to the understanding of the natural origin of human-infecting microsporidia, (ii) revealed unique genetic features of their dramatically reduced genome and (iii) resulted in the correction of their phylogenetic placement among eukaryotes from primitive protozoans to highly evolved organisms related to fungi. Microsporidia might serve as new intracellular model organisms in the future given that gene transfer systems will be developed.

Genetic homology among thirteen Encephalitozoon intestinalis isolates obtained from human immunodeficiency virus-infected patients with intestinal microsporidiosis

The ribosomal DNA internal transcribed spacer sequences of 13 unrelated Encephalitozoon intestinalis isolates obtained from human immunodeficiency virus (HIV)-infected patients with intestinal microsporidiosis were analyzed by gene amplification and DNA sequencing. Among these isolates, we found only one genetic lineage which suggests that E. intestinalis may have a clonal distribution in HIV-infected patients.

Dual microsporidial infection due to Vittaforma corneae and Encephalitozoon hellem in a patient with AIDS

A 46-year-old human immunodeficiency virus-infected Swiss citizen living in Tanzania presented with respiratory, abdominal, and urogenital complaints. Microsporidial spores were isolated from urine and a sinunasal aspirate and were propagated in MRC-5 cell cultures. Western blot analysis and riboprinting identified the sinunasal isolate as Encephalitozoon hellem. Electron microscopic investigation of the urine isolate revealed spores with diplokaryotic nuclei and five to six isofilar coils of the polar tube and sporonts with two or three diplokarya. All stages were enveloped by two membranes, corresponding to a cisterna of host endoplasmic reticulum studded with ribosomes. These characteristics have been described for the genus Vittaforma. Western blot analysis of this isolate revealed a banding pattern identical to that of the Vittaforma corneae reference isolate. Part of the small subunit rRNA gene was amplified, sequenced (239 base pairs), and found to be identical to that of V. corneae. This is the second isolation of V. corneae and the first description of urinary tract infection due to V. corneae in a patient with AIDS.

Microsporidial disease in HIV-infected patients: a report of 42 patients and review of the literature

Microsporidiosis is recognized as an increasingly important infection, particularly in patients with human immunodeficiency virus (HIV) infection. In this retrospective study we have reviewed the clinical features, laboratory findings and management of 42 HIV positive patients co-infected with microsporidia. All patients had spores identified in faeces stained with a modified trichome blue stain. Patients were all markedly immunosuppressed (median CD4 20 cells/microl). Common symptoms included weight loss, diarrhoea, abdominal pain, anorexia and nausea. 29 patients were diagnosed with Enterocytozoon bieneusi infection; 13 were infected with Encephalitozoon intestinalis, and disseminated disease was confirmed in 8. Albendazole therapy in patients with E. intestinalis (but not E. bieneusi) resulted in good clinical response.

Identification of a human isolate of Encephalitozoon cuniculi type I from Italy

A microsporidial strain, obtained from a person with AIDS living in Italy was isolated and cultivated on RK13 (rabbit kidney) cell monolayers. Identification at the species level was performed by immunological and molecular methods. Western blot analysis showed that the human isolate and the Encephalitozoon cuniculi reference strain had similar banding patterns. The small subunit rRNA sequence analysis confirmed the identification of the isolate as E. cuniculi, which is a widespread microsporidian species infecting a wide range of natural hosts, including humans. Moreover, based on the sequence of the rDNA internal transcribed spacer region, this isolate was classified as E. cuniculi type I (rabbit strain), previously reported in six persons with AIDS living in Switzerland. These results provide further information on the geographical distribution of E. cuniculi types.

Renal Encephalitozoon (Septata) intestinalis infection in a patient with AIDS. Post-mortem identification by means of transmission electron microscopy and PCR

We describe the occurrence of renal Encephalitozoon (Septata) intestinalis infection in a 35-year-old AIDS patient who died with disseminated tuberculosis. The patient did not complain of specific symptoms involving the kidney or lower urinary tract during life, but at autopsy, light microscopic examination of the kidney revealed numerous small round or oval bodies in the tubules and tubular cell cytoplasm that were interpreted as intracellular protozoa. Transmission electron microscopy of tissue retrieved from paraffin-embedded samples identified these organisms as microsporidia belonging to the Encephalitozoonidae family, but did not allow definitive identification of the species of infecting parasite. This was made possible only by means of Southern blot hybridization after the polymerase chain reaction, which recognized the micro-organism as E. intestinalis.

Bovine leukemia virus-induced clinical signs and morphological changes of encephalitozoonosis in rabbits

Fourteen three-month-old rabbits spontaneously-infected with the microsporidium Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 were inoculated intravenously with lymphocytes (Ly) from seropositive bovine leukemia virus infected cattle (Ly/BLV) or with fetal lamb kidney cells infected with bovine fetal leukemia (FLK/BLV). Thirteen rabbits were seropositive to BLV at least for a period of three months. Six rabbits died of pulmonary lesions. Chronic inflammatory lesions of encephalitozoonosis were found in six rabbits killed between 454 and 548 days of the observation period. Five animals bore subcutaneous granulomas. Immunohistochemically, E. cuniculi was demonstrated in the inflammatory lesions of rabbits studied. Control animals also spontaneously infected with E. cuniculi did not show clinical signs of encephalitozoonosis. Morphological changes were found incidentally in the form of small glial foci and focal interstitial nephritis in these animals. The combined action of BLV-E. cuniculi on the bodies of rabbits is proposed as a suitable model for the study of encephalitozoonosis in man with human immunodeficiency virus (HIV) infection.

Simple diagnosis of Encephalitozoon sp. microsporidial infections by using a panspecific antiexospore monoclonal antibody

Microsporidia (phylum Microsproa) have recently become recognized as common opportunistic protozoans in the United States and worldwide, particularly affecting immunodeficient patients. Microsporidian organisms within the genus Encephalitozoon are the cause of nephrologic, ophthalmic, pneumologic, gastroenteric, and systemic infections. However, diagnosis of the small spores by light microscopy is difficult, even with newly developed and improved staining techniques. We have developed an anti-Encephalitozoon species monoclonal antibody-based immunoassay for easy diagnosis. A hybridoma was produced and selected following one main criterion: recognition by immunofluorescence of all known Encephalitozoon spores affecting humans. The selected monoclonal antibody-secreting hybridomas were characterized by enzyme-linked immunosorbent assay, immunofluorescence, Western blot, and immunoelectron microscopy using Encephalitozoon species from fresh and fixed samples from patients and from in vitro cultures. In the immunofluorescence assay, one monoclonal antibody, termed 3B6, strongly recognized Encephalitozoon cuniculi, E. hellem, and E. intestinalis. Monoclonal antibody 3B6 bound to other microsporidia (Nosema and Vairimorpha spp.) without cross-reacting with any other parasite, including Enterocytozoon bieneusi, fungus, or bacterium tested. In immunoelectron microscopy assays, monoclonal antibody 3B6 bound to the exospore of Encephalitozoon species, while in Western blot assays, it recognized three to seven antigens with molecular masses ranging from 34 to 117 kDa. We have developed a sensitive and specific monoclonal antibody-based immunoassay to diagnose common microsporidian infections, particularly with Encephalitozoon species. This is a new tool for identifying spores in bodily fluids and biopsy samples and is an efficient diagnostic test. Additionally, monoclonal antibody 3B6 can serve to assess the prevalence of microsporidial infections in immunodeficient and immunocompetent patients.

Specific PCR assay for direct detection of intestinal microsporidia Enterocytozoon bieneusi and Encephalitozoon intestinalis in fecal specimens from human immunodeficiency virus-infected patients

A routine assay based on the PCR was developed for the detection of Enterocytozoon bieneusi and Encephalitozoon intestinalis in fecal samples. Two oligonucleotide primer pairs from a conserved region in the small-subunit rRNA genes of E. bieneusi (primer pair V1 and EB450) and E. intestinalis (primer pair V1 and SI500) were used to amplify microsporidian DNA. We achieved specific amplification of a 382-bp DNA fragment in E. intestinalis and a 353-bp DNA fragment in E. bieneusi. Boiling of the samples appeared to be most effective for DNA extraction. Fecal samples containing fewer than 10 microsporidia gave a positive result in the PCR assay. Fecal specimens from 30 human immunodeficiency virus-infected patients with microsporidiosis and fecal specimens from 42 patients suspected of having microsporidiosis were investigated by the PCR assay. The PCR assay was validated against standard staining methods (the Uvitex 2B and Chromotrope 2R staining methods) and immunofluorescence assay specific for E. intestinalis. This comparative study has shown that PCR improved species determination and can thus be considered a fast and reliable method for the detection and identification of each intestinal species.

Western blot and immunofluorescence analysis of a human isolate of Encephalitozoon cuniculi established in culture from the urine of a patient with AIDS

Microsporidia spores, identified as Encephalitozoon cuniculi (CDC: V282), were isolated from the urine of a patient with acquired immunodeficiency syndrome and disseminated microsporidiosis, established in continuous culture on monkey kidney cells (E6), and antiserum was produced in rabbits. Immunoblot studies that used the patient serum and the rabbit sera against CDC:V282, Encephalitozoon hellem (CDC:0291:V213), and Encephalitozoon intestinalis (CDC:V297) revealed that CDC:V282 and the rabbit isolate of E. cuniculi (ECLD) reacted intensely with the patient's serum and the rabbit anti-CDC:V282, producing a number of bands ranging from 200 to 15 kDa. By contrast, the heterologous antigens (CDC:0291:V213 and CDCV297) reacted minimally. Both CDC:V282 and ECLD isolates of E. cuniculi reacted minimally with the rabbit anti-E. hellem and the rabbit anti-E. intestinalis sera. In the immunofluorescence test, performed on the lung biopsy section of the patient, the rabbit anti-CDC:V282 serum reacted extensively with the spores in the tissue section and produced bright apple green fluorescence. These studies demonstrated that the human (CDC:282) and the rabbit (ECLD) isolates of E. cuniculi were similar in their antigenic profiles but differed considerably from E. hellem and E. intestinalis, and that the patient's serum reacted specifically, strongly, and with equal intensity, with the 2 isolates of E. cuniculi.

A microsporidian isolated from an AIDS patient corresponds to Encephalitozoon cuniculi III, originally isolated from domestic dogs

The ribosomal DNA internal transcribed spacer (ITS) region of a recently cultured human Encephalitozoon cuniculi isolate was analyzed by gene amplification and DNA sequencing. Restriction endonuclease digestion (FokI) and double-stranded DNA heteroduplex mobility shift analysis were performed to determine their utility for strain differentiation. The human E. cuniculi isolate was identical to E. cuniculi III, which had been isolated only from domestic dogs until now. The patient providing the isolate owned a pet dog, but no microsporidia were detected in the pet's urine.

Experimental model for human intestinal microsporidiosis in interferon gamma receptor knockout mice infected by Encephalitozoon intestinalis

Interferon gamma receptor knockout mice developed a chronic infection when inoculated with spores of Encephalitozoon intestinalis which is a cause of intestinal microsporidiosis in AIDS patients. The infection was evaluated by enumeration of the spores of the parasite shed in the stools, histological examination and follow up over a period of six months. A dose-response was demonstrated since higher numbers of spores were excreted and more infection sites were found in mice which were given an increased quantity of parasites. In infected wild type mice, the number of excreted spores decreased until day 16 post-inoculation, then spores were detected sporadically in low numbers. These data confirmed the role of IFN-gamma in the control of E. intestinalis infection. The infection was not lethal suggesting that other factors are involved in regulation of the parasite infection. This model, with the long survival time of the animals together with the measurable quantity of spores shed in the stools will be useful for testing potential therapeutical agents.

Generalized encephalitozoonosis in a Jersey wooly rabbit

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Diagnosis of disseminated microsporidian Encephalitozoon hellem infection by PCR-Southern analysis and successful treatment with albendazole and fumagillin

A 37-year old AIDS patient presented with foreign body sensation. Microsporidia were detected in smears from a conjunctival swab and urine sediment stained with calcofluor and a modified trichrome blue stain and by indirect fluorescent-antibody staining with murine polyclonal antiserum raised against Encephalitozoon hellem. This antiserum cross-reacted with other Encephalitozoon species, so PCR was performed to amplify the microsporidian ribosomal DNA (rDNA) with pan-Encephalitozoon primers. The PCR DNA products from the urine and conjunctival clinical specimens, along with the tissue culture-derived microsporidian controls, were assayed by Southern analysis with oligonucleotide probes specific for Encephalitozoon cuniculi, E. hellem, and Encephalitozoon (Septata) intestinalis. The PCR product amplified from the urine specimen hybridized with the E. hellem probe only, while insufficient DNA was amplified from the conjunctiva specimen for detection by Southern analysis. For corroboration of the PCR-Southern analysis results, aliquots of the urine and conjunctiva specimens were seeded onto RK-13 cell monolayers. The rDNA extracts of the cultured microsporidia were amplified by PCR with pan-Encephalitozoon primers, and the PCR DNA products were subjected to digestion with restriction endonuclease FokI. The amplified rDNA of both the urine and conjunctiva isolates generated digestion patterns that were identified to the E. hellem PCR rDNA digestion pattern. In addition, double-stranded heteroduplex mobility shift analysis with these PCR products indicated that the urine and conjunctiva isolates were identical to each other and to E. hellem. The patient was treated with albendazole and topical fumagillin and responded rapidly, with no recurrence of ophthalmologic signs. The results of this study demonstrate that PCR-Southern analysis provides a basis for distinguishing E. cuniculi, E. hellem, and E. intestinalis in clinical specimens.

Immunologic and molecular characteristics of Encephalitozoon-like microsporidia isolated from humans and rabbits indicate that Encephalitozoon cuniculi is a zoonotic parasite

To assess the zoonotic potential of Encephalitozoon-like microsporidia, we isolated and cultivated spores from specimens of urine, respiratory secretions, and stool from six patients infected with human immunodeficiency virus and from nine rabbits. Because spores of Encephalitozoon-like species are indistinguishable by microscopy, we characterized the isolates by western blot analysis and by restriction enzyme analysis of the small subunit (SSU) rDNA after amplification by the polymerase chain reaction. We identified Septata intestinalis in one patient and Encephalitozoon hellem in two symptomatic patients. Encephalitozoon cuniculi was found in all rabbits and in three patients. One of these patients had clinical manifestations of infection with this parasite (severe interstitial pneumonitis). We observed abatement of symptoms and cessation of parasite excretion when these patients were treated with albendazole. Our findings suggest that E. cuniculi may be pathogenic in humans and that it is a zoonotic parasite.

Encephalocytozoon intestinalis-specific monoclonal antibodies for laboratory diagnosis of microsporidiosis

Two monoclonal antibodies which can be used for the unambiguous identification by fluorescence microscopy of Encephalitozoon intestinalis spores in clinical specimens are described. Monoclonal antibody Si91 is specific for the extruded polar filament, and Si13 recognizes the surfaces of E. intestinalis spores. No cross-reaction with spores of Encephalitozoon hellem was observed. Immunogold electron microscopy confirmed the specific reactivities of both antibodies. Combined in an indirect immunofluorescence assay, these antibodies are used to identify spores in feces. Although there was some cross-reaction with fecal bacteria and fungi, the typical morphology of the extruded polar filaments enabled proper identification of the E. intestinalis spores. Parasites could also be demonstrated to be present in urine, nasal swabs, lung brush biopsy specimens, and bronchoalveolar lavage fluid from a patient with disseminated infection with E. intestinalis. The use of these monoclonal antibodies facilitates the detection and species determination of E. intestinalis in clinical specimens.

Autopsy verification of Encephalitozoon intestinalis (microsporidiosis) eradication following albendazole therapy

Microsporidian infections are increasingly recognized as an important cause of morbidity for persons infected with the human immunodeficiency virus. Encephalitozoon (formerly Septata) intestinalis is a recently described microsporidian that causes intestinal and disseminated infections in severely immunocompromised patients with acquired immunodeficiency syndrome. Several studies suggest that albendazole is an effective therapy for E intestinalis infection. However, relapses of symptoms and reappearance of microsporidian spores in diagnostic specimens have been reported following treatment in some cases. Because these results are based on examination of feces or cytologic specimens with an inherent sampling bias, it would be ideal to have autopsy data on the complete tissue evaluation of major organ systems of patients who had antemortem E intestinalis infection treated with albendazole. This report describes an acquired immunodeficiency syndrome patient with diarrhea and wasting syndrome associated with E intestinalis infection. Treatment with albendazole produced relief of his clinical symptoms and eliminated microsporidian spores in his feces. Following his death from other causes, an autopsy was performed. Comprehensive microscopic examination of all major organs revealed no evidence of residual microsporidian infection, suggesting parasitologic cure of E intestinalis with albendazole. The postmortem finding of complete clearance of microsporidia from body tissues is significant for future albendazole treatment of patients infected with E intestinalis and provides strong support for the value of the autopsy in evaluating the therapeutic efficacy of antimicrobials in emerging infections.

Characterization of Encephalitozoon (Septata) intestinalis isolates cultured from nasal mucosa and bronchoalveolar lavage fluids of two AIDS patients

Microsporidia are obligate intracellular protozoan parasites that can cause opportunistic infections in AIDS patients. Species from five genera of microsporidia are presently known to infect man. One species, Septata intestinalis originally was detected in stool specimens of individuals with chronic diarrhea and subsequently was found to disseminate to the kidneys, lungs, and nasal sinuses. This organism has since been reclassified as Encephalitozoon and in this study, we report the culture of Encephalitozoon intestinalis from a bronchoalveolar lavage specimen and a nasal mucus aspirate of two AIDS patients living in the USA. The bronchoalveolar and nasal microsporidian isolates grew in several continuous cell lines including RK-13, MDCK, HT-29, Caco-2, Vero, and I047. Transmission electron microscopy of the clinical and cell culture specimens revealed that the new isolates appeared to be E. intestinalis based on morphology and growth of organisms in septated membrane-bound parasitophorous vacuoles. The new E. intestinalis isolates were characterized and compared with the first isolated E. intestinalis that was cultured from stool to confirm their identity and to determine if there existed any minor differences, as seen in the closely related Encephalitozoon cuniculi strains. By the methods of sodium dodecyl sulfate-polyacrylamide gel electrophoresis staining for proteins and carbohydrates, Western blot immunodetection, and polymerase chain reaction-based methods with restriction endonuclease digestion, double-stranded DNA heteroduplex mobility shift analysis, and DNA sequencing of the ribosomal DNA intergenic spacer region, the new isolates were identical to each other and to the reference isolate of E. intestinalis. In addition, with any of these methods, the E. intestinalis organisms could be distinguished from the three E. cuniculi strains, Encephalitozoon hellem, and Vittaforma corneae, which is important for diagnostics, therapeutic strategies, and epidemiology.

Immunologically confirmed disseminated, asymptomatic Encephalitozoon cuniculi infection of the gastrointestinal tract in a patient with AIDS

Microsporidia are obligate intracellular protozoan parasites that infect a broad range of vertebrates and invertebrates. They are increasingly recognized as human pathogens, especially in patients infected with human immunodeficiency virus (HIV). Organisms of the genus Encephalitozoon have been implicated as a major cause of disseminated microsporidian infections in persons with AIDS. Until recently, E. hellem was the only Encephalitozoon species confirmed by antigenic or nucleic acid methods to have infected humans. We describe the clinical course and morphological features of a case of disseminated microsporidian infection with Encephalitozoon cuniculi in an HIV-infected patient with chronic sinusitis, rhinitis, and keratoconjunctivitis. Parasites were found in conjunctival swab, nasal discharge, sputum, urine, stool, and duodenal biopsy specimens, but no pulmonary, renal, or gastrointestinal symptoms were documented. The patient was treated with albendazole (400 mg po b.i.d.), resulting in complete remission of his ocular and nasal symptoms, and microsporidian spores disappeared from all sites. To our knowledge, this case is only the second of E. cuniculi infection in humans that has been confirmed by either antibody- or nucleic acid-based methods, and it is the first in which an Encephalitozoon species has been found in the intestinal tract of a human. Microsporidiosis is an important emerging opportunistic infection in HIV-infected patients and, as documented in this report, has an expanding clinicopathologic spectrum.

Disseminated Encephalitozoon (Septata) intestinalis infection in a patient with AIDS: novel diagnostic approaches and autopsy-confirmed parasitological cure following treatment with albendazole

Encephalitozoon intestinalis is a recently described microsporidian which causes intestinal and disseminated infections in severely immunocompromised patients with AIDS. Preliminary data suggest that albendazole can be an effective therapy for patients with E. intestinalis infection. However, relapses have been reported following treatment in some cases. These results were based upon examination of cytologic, biopsy, or stool samples with an inherent sampling bias. This report documents the first postmortem evaluation of a patient with E. intestinalis infection treated with albendazole. Antemortem microsporidial diagnosis was performed on nasal mucosal smear and duodenal biopsy specimens by electron microscopy and a newly developed indirect fluorescent-antibody method based upon in vitro cultivation of the organism. This case represents the initial report of using nasal cytologic specimens for ultrastructural and antibody-based species-level diagnosis of microsporidiosis. Following successful treatment of this infection with albendazole, the patient died of other causes. A thorough autopsy examination failed to reveal the presence of E. intestinalis in any tissue, providing confirmatory evidence for a complete parasitological cure with albendazole.

Encephalitozoon-like organisms in patients with alveolar hydatid disease: cell culture, ultrastructure, histoimmunochemical localization and seroprevalence

We found Encephalitozoon-like organisms in an in vitro culture of a human liver lesion which was due to larval Echinococcus multilocularis. The organisms developed in the same fashion as an Encephalitozoon cuniculi. The spores that developed in parasitophorous vacuoles were 2.0-2.6 x 1.1-1.5 microns; each contained a single nucleus and 4-5 polar tubule coils, closely resembling E. cuniculi in its ultrastructure. Mature spores were collected from the supernatants by the use of Percoll centrifugation resulting in the banding of the spores on continuous gradients. We prepared three sorts of spores which were different in buoyant density in 0.15 M NaCl: 1.05-1.07 g/ml spores, 1.12 g/ml spores, and spores of over 1.14 g/ml. Polyclonal antibodies to a pool of each spore preparation were produced in a rabbit and applied to the detection of microsporidian antigen in situ. The histoimmunoperoxidase (HIP) procedure was used to detect the microsporidian antigen in echinococcal liver lesions from patients with alveolar hydatid disease (AHD). Ten echinococcal liver lesions from different AHD patients were examined and four were found to be positive in the HIP test. The Percoll-separated spores were also used as an antigen to detect for antibodies in the sera from the patients with AHD by Western blotting. Antibodies were detected in 62 (52%) of the 119 AHD patients and in only 8 (5%) of the 159 normal healthy individuals.

[A case of disseminated Encephalitozoon intestinalis microsporidiosis in an AIDS patient in Nîmes]

The pathogene's role importance of the microsporidia in nature is considerable. The human being, easily in contact, presents clinical manifestations only with some of them and in a very occasional manner. The increased frequency of the immunodepression has permitted to describe recently a new protozoon, Encephalitozoon intestinalis (alias Septata intestinalis) of the family of the Glugeidae and the human illness of which it is the agent. This parasitose is interesting to be presented because of its rarity and its circulation to organs far from one another. The diagnostic has been done thanks to the only optic microscope and confirmed from its visible efficacity of one cure of albendazole. The pyrimethamine could present a relative efficiency on a relapse of the sinusitis.

Isolation and identification of Encephalitozoon hellem from an Italian AIDS patient with disseminated microsporidiosis

Microsporidia are primitive mitochondria-lacking spore-forming eukaryotic protozoa that infect a wide variety of animals and also humans. Of the five genera (Encephalitozoon, Enterocytozoon, Septata, Nosema and Pleistophora) that cause infections in humans, Enterocytozoon bieneusi, Septata intestinalis, and Encephalitozoon hellem are being increasingly identified in patients with acquired immunodeficiency syndrome (AIDS). E. bieneusi causes gastrointestinal disease, S. intestinalis causes gastrointestinal and disseminated disease, and E. hellem causes ocular as well as disseminated disease. We have established in continuous culture a strain of microsporidia isolated from the urine and throat washings of an Italian AIDS patient and identified it as Encephalitozoon hellem, based on its ultrastructural morphology, antigenic pattern, and polymerase chain reaction-amplified small subunit ribosomal RNA. We believe that this is the first time that a strain of microsporidia has been isolated from the throat washings of a patient with microsporidiosis.

Diagnostic approaches for Encephalitozoon infections in patients with AIDS

In conclusion, at the current time the most important task of the laboratory for proper clinical management of the patient with microsporidiosis is to perform genus-level diagnosis of the agent, i.e. distinguishing Encephalitozoon sp. infection from other microsporidial agents including Septata, Enterocytozoon, Nosema, and Pleistophora. This can be performed in any well-equipped pathology department with access to electron microscopy. If species identification is desired, we currently recommend consultation with one of several laboratories specializing in this area until diagnostic reagents become more widely available.

Reversible renal failure caused by a microsporidian infection

OBJECTIVE

To report a case of renal failure associated with microsporidian infection in an HIV-seropositive patient.

DESIGN

Case report.

SETTING

Chelsea and Westminster Hospital, London, England, UK.

PATIENT

An HIV-seropositive patient presented febrile with abdominal pain who developed renal failure. Renal biopsy and urinalysis showed infection with a microsporidian of the genus Encephalitozoon.

INTERVENTION

Treatment with albendazole (400 mg) twice daily was associated with disappearance of infection from the urine, clinical improvement and return of renal function virtually to normal.

CONCLUSION

HIV-seropositive individuals with renal failure should have urine screened for microsporidia. The administration of albendazole in such cases may reverse renal failure.

Detection of microsporidia by indirect immunofluorescence antibody test using polyclonal and monoclonal antibodies

During a screening for monoclonal antibodies (MAbs) to the microsporidian Encephalitozoon hellem, three murine hybridoma cell lines producing strong enzyme-linked immunosorbent assay (ELISA) reactivities were cloned twice, were designated C12, E9, and E11, and were found to secrete MAbs to the immunoglobulin M isotype. On subsequent ELISAs, the three MAbs reacted most strongly to E. hellem, and they reacted somewhat less to Encephalitozoon cuniculi and least to Nosema corneum, two other microsporidian species. The MAbs produced values of absorbance against microsporidia that were at least three times greater than reactivities obtained with control hybridoma supernatants or with uninfected host cell proteins used as antigens. By Western blot immunodetection, the three MAbs detected three E. hellem antigens with relative molecular weights (M(r)s) of 62, 60, and 52 when assayed at the highest supernatant dilutions producing reactivity. At lower dilutions, the MAbs detected additional proteins with M(r)s of 55 and 53. By using indirect immunofluorescence antibody staining, the MAbs, as well as hyperimmune polyclonal murine antisera raised against E. cuniculi and E. hellem, were able to detect formalin-fixed, tissue culture-derived E. cuniculi and E. hellem and two other human microsporidia, Enterocytozoon bieneusi and Septata intestinalis, in formalin-fixed stool and urine, respectively. E. bieneusi, however, stained more intensely with the polyclonal antisera than with the MAbs. Neither the MAbs nor the hyperimmune murine polyclonal antibodies detected Cryptosporidium, Giardia, Trichomonas, or Isospora spp. At higher concentrations, the polyclonal antisera did stain N. corneum and yeast cells. The background staining could be absorbed with Candida albicans. These results demonstrate that polyclonal antisera to E. cuniculi and E. hellem, as well as MAbs raised against E. hellem, can be used for indirect immunofluorescence antibody staining to detect several species of microsporidia known to cause opportunistic infections in AIDS patients.

Inhibition of the spore polar filament extrusion of the microsporidium, Encephalitozoon hellem, isolated from an AIDS patient

Spores of the microsporidian parasitic protozoan Encephalitozoon hellem were purified and incubated at 37 degrees C in a solution with an electrolyte composition similar to that of mammalian extracellular fluid, and in solution in which the calcium had been replaced with 0.2 mM EGTA. Polar filament extrusion (germination) was monitored by both scanning electron microscopy and light microscopy. Germination was pH-dependent, with optima at pH 7.4 and 9.5, and was significantly greater in the presence of medium calcium. Hydrogen peroxide caused a concentration-dependent increase in germination that was also reduced in a calcium-free medium. Four agents were found to inhibit spontaneous and H2O2-stimulated polar filament extrusion: the microfilament disrupter, cytochalasin D; the microtubule disrupter, demecolcine; the calcium channel blocker, nifedipine; and the antifungal agent, itraconazole. These results are consistent with the existence of a calcium-channel-mediated step, and requirements for an F-actin- and for a tubulin-containing element in the germination process of the spore of this parasite. Nifedipine, cytochalasin D and itraconazole all have different sites of action and were therefore able to potentiate one another when used in paired combination to inhibit germination.

Characterization of Encephalitozoon hellem (Microspora) isolated from the nasal mucosa of a patient with AIDS

A microsporidium of the genus Encephalitozoon was isolated into culture from the nasal epithelium of a patient with AIDS. It was compared with in vitro isolates of Encephalitozoon cuniculi and the type isolate of Encephalitozoon hellem by SDS-PAGE and by Western blotting with murine antisera raised to E. cuniculi, E. hellem and the nasal isolate, monoclonal antibodies raised to E. cuniculi and sequential sera from the patient. All tests showed similarities between E. hellem and the nasal isolate but differences between these two isolates and E. cuniculi. Minor protein differences between E. hellem and the nasal isolate were not considered sufficient to separate them at the specific level. The new isolate is named the Wainwright isolate of E. hellem. The ultrastructure of the Wainwright isolate in vitro was similar to that of the parasite in vivo but there was a greater tendency for disruption of the parasitophorous vacuoles. The deposition of the electron-dense surface coat on the sporogonic stages of E. hellem, as a uniform layer which later thickens, is in contrast to its deposition as broad bands, which later join up, in E. cuniculi. This may be a useful character in distinguishing the species without recourse to analysis of protein profiles.

Microsporidial keratoconjunctivitis in a patient with AIDS

A male patient is described with acquired immune deficiency syndrome (AIDS) who developed chronic keratoconjunctivitis and chronic sinusitis due to infection with the microsporidian Encephalitozoon cuniculi. Diagnosis was confirmed by electron microscopic examination of conjunctival epithelial cells and nasal polypectomy specimens. Treatment with propamidine isethionate 0.1% (Brolene) eye drops six times daily led to a prompt resolution of the keratoconjunctivitis.

Ultrastructure of the development of a species of Encephalitozoon cultured from the eye of an AIDS patient

Human fibroblast cell cultures inoculated with microsporidia-infected corneal scrapings from an AIDS patient were fixed in situ and examined by scanning and transmission electron microscopy. The parasite grew prolifically and all developmental stages were observed. Meronts underwent binary fission and the daughter cells transformed into elongate, chain-like sporonts that eventually separated into sporoblasts. The formation of components of the mature spores is described. The parasite, a species of Encephalitozoon, underwent development both in the cytoplasm and within a parasitophorous vacuole, distinguishing it from the morphologically similar species E. cuniculi and E. hellem, both of which have been described from lesions in the human eye and have been reported to develop exclusively within a parasitophorous vacuole.