Modified technique to recover microsporidian spores in sodium acetate-acetic acid-formalin-fixed fecal samples by light microscopy and correlation with transmission electron microscopy

Challenges in the diagnosis of microbial keratitis: A detailed review with update and general guidelines

The incidence of microbial keratitis (MK) is variable worldwide with an estimated 1.5–2 million cases of corneal ulcers in developing countries. The complications of MK can be severe and vision threatening. Therefore, proper diagnosis of the causative organism is essential for early successful treatment. Accurate sampling of microbiological specimens in MK is an important step in identifying the infective organism. Corneal scrapping, tear samples and corneal biopsy are examples of specimens obtained for the investigative procedures in MK. Ophthalmologists especially in an emergency room setting should be aware of the proper sampling techniques based on their microbiology-related basic information for each category of MK. This review article briefly describes the clinical presentation and defines in details the best updated diagnostic methods used in different types of MK. It can be used as a guide for ophthalmology trainees and general ophthalmologists who may be handling such cases at initial presentation.

Microsporidial keratoconjunctivitis after rugby tournament, Singapore

We investigated an outbreak of 47 probable and 6 confirmed cases of microsporidial keratoconjunctivitis involving participants of an international rugby tournament in Singapore in April 2012.The mode of transmission was eye contact with soil. Vittaforma corneae was identified in 4 of 6 corneal scrapings and in 1 of 12 soil water samples.

Microsporidial keratoconjunctivitis after rugby tournament, Singapore

We investigated an outbreak of 47 probable and 6 confirmed cases of microsporidial keratoconjunctivitis involving participants of an international rugby tournament in Singapore in April 2012.The mode of transmission was eye contact with soil. Vittaforma corneae was identified in 4 of 6 corneal scrapings and in 1 of 12 soil water samples.

Prevalence of microsporidium and other intestinal parasites in children from malatya, Turkey

Parasite infections are common during the critical developmental period in children. The occurrences of intestinal parasites are also common in orphanage, nurseries and schools in Turkey. The study was carried out to determine the percentage of microsporidium and intestinal parasites in children from Malatya, Turkey. This study was carried out at the Department of Parasitology of Inonu University, Turgut Ozal Medical Center, during January-December 2006. Totally, 1,181 stool samples were examined using the native-Lugol, sedimentation-techniques, modified trichrome (MTS), acid-fast-trichrome stain and calcofluor staining methods. In addition, perianal region material was taken from the children to examine with cellophane tape method. Power analyses were performed for statistical analyses used. Microsporidia were found in 92 (7.8%) of the samples, and also intestinal parasites were detected in 329 (27.8%). The numbers of infections according to the species were as follows: 69 (5.8%) Entamoeba coli, 7 (0.6%) Blastocystis hominis, 114 (9.7%) Giardia intestinalis, 15 (1.3%) Iodomoeba butchlii, 8 (0.7%) Dientamoeba fragilis, 7 (0.6%) Taenia spp. 70 (5.9%) Enterobius vermicularis, 11 (0.9%) Hymenolepis nana, 25 (2.1%) Trichomonas intestinalis, 1 (0.1%) Ascaris lumbricoides and 2 (0.2%) Chilomastix mesnilii. Also, greater than 90% power values were achieved for statistical analyses. Whereas the detection rates of microsporidium and intestinal parasites were found to be low, it was concluded that in addition to intestinal parasites, microsporidium should be also searched for in children with complaints of intestinal system.

Outbreak of microsporidiosis caused by Enterocytozoon bieneusi in falcons

Four falcons from a private collection of 137 falcons in Abu Dhabi (UAE) died suddenly in summer 2005. In order to screen for a possible disease among the remaining falcons in the aviary, all other birds were caught, examined and treated if necessary. Most of the falcons suffered from massive lice infestation and 74 falcons additionally from a heavy Caryospora sp. burden. Endoscopy revealed yellowish plaques on intestines, livers or kidneys in 70 birds (51.1% morbidity). Proliferative serositis was seen in 17 out of 24 necropsied birds with plaques on intestines, livers or kidneys, which did not resemble any known disease in falcons. However, apart from 20 falcons, which died within a 6-week period after the initial examinations due to advanced disease stages, all other falcons responded well to the treatment with dimetridazole (Emtryl), indicating protozoal disease. Immunohistochemistry confirmed the presence of microsporidial antigen. The final diagnosis of Enterocytozoon (E.) bieneusi genotype D was confirmed with materials from 6 birds by PCR and sequencing. To our knowledge this is the first report of microsporidiosis caused by E. bieneusi in raptors in general and in falcons in particular. However, it is still unclear for how long E. bieneusi was present in the falcon flock, and which role it played in the development of the disease. Predisposing factors such as high temperature and overcrowding in the aviary induced immune suppression causing massive lice infestation as well as coccidiosis, thus paving the way for invasion with microsporidial spores.

Simultaneous detection of four human pathogenic microsporidian species from clinical samples by oligonucleotide microarray

Microsporidian species have been rapidly emerging as human enteric pathogens in immunocompromised and immunocompetent individuals in recent years. Routine diagnostic techniques for microsporidia in clinical laboratories are laborious and insensitive and tend to underestimate their presence. In most instances, they are unable to differentiate species of spores due to their small sizes and similar morphologies. In this study, we report the development of another protozoan oligonucleotide microarray assay for the simultaneous detection and identification to the species level of four major microsporidian species: Enterocytozoon bieneusi, Encephalitozoon cuniculi, Encephalitozoon hellem, and Encephalitozoon intestinalis. The 18S small-subunit rRNA gene was chosen as the amplification target, labeled with fluorescence dye, and hybridized to a series of species-specific oligonucleotide probes immobilized on a microchip. The specificity and sensitivity of the microarray were clearly demonstrated by the unique hybridization profiles exhibited by each species of microsporidian tested and its ability to detect as few as 10 spores. In order to assess the applicability of this microarray in a clinical setting, we conducted microarray assays of 20 fecal samples from AIDS patients. Twelve of these samples were positive for the presence of microsporidia and could be confidently identified; 11 of them were positive for more than one species. Our results suggested that this microarray-based approach represents an attractive diagnostic tool for high-throughput detection and identification of microsporidian species in clinical and epidemiological investigations.

Molecular techniques for detection, species differentiation, and phylogenetic analysis of microsporidia

Microsporidia are obligate intracellular protozoan parasites that infect a broad range of vertebrates and invertebrates. These parasites are now recognized as one of the most common pathogens in human immunodeficiency virus-infected patients. For most patients with infectious diseases, microbiological isolation and identification techniques offer the most rapid and specific determination of the etiologic agent. This is not a suitable procedure for microsporidia, which are obligate intracellular parasites requiring cell culture systems for growth. Therefore, the diagnosis of microsporidiosis currently depends on morphological demonstration of the organisms themselves. Although the diagnosis of microsporidiosis and identification of microsporidia by light microscopy have greatly improved during the last few years, species differentiation by these techniques is usually impossible and transmission electron microscopy may be necessary. Immunfluorescent-staining techniques have been developed for species differentiation of microsporidia, but the antibodies used in these procedures are available only at research laboratories at present. During the last 10 years, the detection of infectious disease agents has begun to include the use of nucleic acid-based technologies. Diagnosis of infection caused by parasitic organisms is the last field of clinical microbiology to incorporate these techniques and molecular techniques (e.g., PCR and hybridization assays) have recently been developed for the detection, species differentiation, and phylogenetic analysis of microsporidia. In this paper we review human microsporidial infections and describe and discuss these newly developed molecular techniques.

Enterocytozoon bieneusi in AIDS: symptomatic relief and parasite changes after furazolidone

AIMS

To investigate changes in morphology of the developmental stages of Enterocytozoon bieneusi and symptomatic relief observed in AIDS patients after treatment with furazolidone.

METHODS

Six AIDS patients with symptomatic E bieneusi infection of the small intestine were treated with a course of furazolidone. All patients had a weekly monitoring of parasite shedding in stool by light microscopy during and after treatment. At the end of the treatment, duodenal biopsy specimens obtained from three patients were studied by transmission electron microscopy by two pathologists who were unaware of the patients' treatment.

RESULTS

All patients showed both clinical and parasitological response with transient clearance or decrease of spore shedding in stool. After treatment, alterations in faecal spores were observed in all patients by light microscopy, and ultrastructural changes in E bieneusi at all stages of the life cycle were demonstrated in biopsy specimens of the three patients who underwent post-treatment endoscopy.

CONCLUSIONS

The clinical benefit seen after treatment with furazolidone in six AIDS patients with E bieneusi intestinal infection may be due to damage to the developmental stages causing a partial inhibition to reproduction of the parasite.