Ultrastructural examination of two cases of stromal microsporidial keratitis

Rauz, Saaeha; Tuft, Stephen; Dart, John K.G.; Bonshek, Richard; Luthert, Philip J.; Curry, Alan

doi:10.1099/jmm.0.45524-0

Cited by 47 publications

(38 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Apart from this first case from Australia, T. hominis was identified in an immunocompetent African immigrant in the United Kingdom as causal agent of a stromal keratitis (231).…”

Section: Trachipleistophora Sppmentioning

confidence: 99%

“…Up to now, four cases of human infections are on record, three of them related to eye infections in immunocompetent patients from the United States and Europe (101,231,253) and one presenting as an urinary tract infection in a patient with AIDS living in Africa, who had a concurrent infection with E. hellem (75). Phylogenetic analysis based on rRNA gene sequences (Fig.…”

Section: Vittaforma Sppmentioning

confidence: 99%

See 1 more Smart Citation

Zoonotic Potential of the Microsporidia

2005

View full text Add to dashboard Cite

Microsporidia are long-known parasitic organisms of almost every animal group, including invertebrates and vertebrates. Microsporidia emerged as important opportunistic pathogens in humans when AIDS became pandemic and, more recently, have also increasingly been detected in otherwise immunocompromised patients, including organ transplant recipients, and in immunocompetent persons with corneal infection or diarrhea. Two species causing rare infections in humans, Encephalitozoon cuniculi and Brachiola vesicularum, had previously been described from animal hosts (vertebrates and insects, respectively). However, several new microsporidial species, including Enterocytozoon bieneusi, the most prevalent human microsporidian causing human immunodeficiency virus-associated diarrhea, have been discovered in humans, raising the question of their natural origin. Vertebrate hosts are now identified for all four major microsporidial species infecting humans (E. bieneusi and the three Encephalitozoon spp.), implying a zoonotic nature of these parasites. Molecular studies have identified phenotypic and/or genetic variability within these species, indicating that they are not uniform, and have allowed the question of their zoonotic potential to be addressed. The focus of this review is the zoonotic potential of the various microsporidia and a brief update on other microsporidia which have no known host or an invertebrate host and which cause rare infections in humans

show abstract

“…Apart from this first case from Australia, T. hominis was identified in an immunocompetent African immigrant in the United Kingdom as causal agent of a stromal keratitis (231).…”

Section: Trachipleistophora Sppmentioning

confidence: 99%

Section: Vittaforma Sppmentioning

confidence: 99%

Zoonotic Potential of the Microsporidia

2005

View full text Add to dashboard Cite

show abstract

“…In the second reported case of V. corneae infection, dual microsporidial infection was detected in a patient with AIDS-Encephalitozoon hellem in the sinonasal aspirate and V. corneae in the urine (3), indicating that V. corneae is capable of dissemination and survival in deep tissues, at least in an immunocompromised host. Three further cases involving V. corneae infection of the corneal stroma of immunocompetent patients were published (9,10,18). In addition to these confirmed cases, there is molecular evidence (obtained by PCR) for Vittaforma infections as a cause of keratitis in India (15 cases) (12) and of enteritis in Portugal (25 cases) (23).…”

mentioning

confidence: 99%

“…One patient with keratitis due to V. corneae was treated with topical steroids and broad-spectrum antibiotics but ultimately required a corneal transplant (2). Another patient was treated initially with topical acyclovir and steroid, but penetrating keratoplasty was performed later and he was given two courses of oral albendazole (400 mg daily), each for 14 days, and no microsporidia were detected in a biopsy of the rejected graft 6 months later (18). A third patient underwent penetrating keratoplasty as well but was not treated with albendazole (10), and another patient was treated with both topical fumagillin bicyclohexylammonium salt and oral albendazole but failed to improve or control the progression of the infection after lamellar keratoplasty (9).…”

mentioning

confidence: 99%

Analysis of the β-Tubulin Gene from Vittaforma corneae Suggests Benzimidazole Resistance

Franzen

Salzberger

2008

Antimicrob Agents Chemother

View full text Add to dashboard Cite

We amplified, cloned, and sequenced the ␤-tubulin gene of Vittaforma corneae, a microsporidium causing human infections. The ␤-tubulin gene sequence has a substitution at Glu 198 (with glutamine), which is one of six amino acids reported to be associated with benzimidazole sensitivity. Benzimidazoles were assayed for antimicrosporidial activity and showed poor parasite inhibition.Microsporidia are obligate intracellular protozoan parasites that have emerged as major opportunistic human pathogens since the onset of the AIDS pandemic (6, 11). Vittaforma corneae is responsible for keratitis in otherwise healthy persons (2, 9, 10, 18), but disseminated infections have occurred in human immunodeficiency virus-infected patients as well (3). V. corneae was first described as Nosema corneum in a stromal biopsy from a non-human immunodeficiency virus-infected man who suffered from central disciform keratitis for 18 months (2). The parasite was cultivated in cell culture and identified as a new species, N. corneum (19). Infection with this organism was subsequently established in athymic mice (20), and new taxonomically significant features found warranted placing this organism within a new genus, Vittaforma, as V. corneae (21). In the second reported case of V. corneae infection, dual microsporidial infection was detected in a patient with AIDS-Encephalitozoon hellem in the sinonasal aspirate and V. corneae in the urine (3), indicating that V. corneae is capable of dissemination and survival in deep tissues, at least in an immunocompromised host. Three further cases involving V. corneae infection of the corneal stroma of immunocompetent patients were published (9,10,18). In addition to these confirmed cases, there is molecular evidence (obtained by PCR) for Vittaforma infections as a cause of keratitis in India (15 cases) (12) and of enteritis in Portugal (25 cases) (23).Benzimidazoles are widely used as anthelmintic drugs in veterinary and human medicine and have been used as antifungal agents in agriculture. Albendazole is one of the most commonly used drugs for treating microsporidiosis in humans (5). Infections with Encephalitozoon spp. respond especially well to therapy with albendazole, whereas infections with Enterocytozoon bieneusi do not respond to albendazole, and the sequence of the ␤-tubulin gene of E. bieneusi suggests that this species is resistant to albendazole (1,5). No clinical data about the response of Vittaforma infections to albendazole are available, and molecular data on the ␤-tubulin gene are not available for this species either. We therefore tested the susceptibility of V. corneae to different benzimidazoles in vitro and amplified, cloned, and sequenced the ␤-tubulin gene of V. corneae.MRC-5 cells were seeded on 24-well culture plates at a concentration of 5 ϫ 10 5 /ml in minimal essential medium and incubated overnight to confluence. Confluent monolayers of cells were inoculated with 2 ϫ 10 6 microsporidian spores (V. corneae and E. cuniculi as a control). Three hours later, noninternalized sp...

show abstract

“…Many species of microsporidia are pathogenic to animals (7,28), and these are also confirmed to cause opportunistic infection in humans (36). These organisms cause infection not only of human digestive tracts but also of many other organs, including eyes (25,36). In past reports, microsporidial keratitis usually was found to occur as epithelial keratitis in patients with AIDS (1,11,(22)(23)(24)37) and as stromal disease in immunocompetent individuals (34)(35).…”

mentioning

confidence: 99%

Microsporidial Keratitis in Patients with Hot Springs Exposure

Fan

Chen

et al. 2012

J Clin Microbiol

View full text Add to dashboard Cite

This retrospective study included 10 eyes of 9 patients diagnosed with microsporidial keratitis. All of them were known to contract this disease after taking baths in hot springs. The disease was diagnosed based on detecting microsporidia in corneal scrapings using Gram stain and the modified Kinyoun's acid-fast stain. The specimens from the last six patients were subjected to PCR and then sequencing. All of them revealed that the microorganism identified has a high similarity to Vittaforma corneae. Repeated debridement of the epithelial lesions successfully eradicated the microsporidial infection in all nine patients.

show abstract

Ultrastructural examination of two cases of stromal microsporidial keratitis

Cited by 47 publications

References 48 publications

Zoonotic Potential of the Microsporidia

Zoonotic Potential of the Microsporidia

Analysis of the β-Tubulin Gene from Vittaforma corneae Suggests Benzimidazole Resistance

Microsporidial Keratitis in Patients with Hot Springs Exposure

Contact Info

Product

Resources

About