Aetiological study of the presumed ocular histoplasmosis syndrome in the Netherlands.
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AIM: To investigate whether presumed ocular histoplasmosis syndrome in the Netherlands is caused by Histoplasma capsulatum and whether other risk factors might play a role in the pathogenesis of this syndrome. METHODS: 23 patients were clinically diagnosed as having presumed ocular histoplasmosis syndrome based on the following criteria: peripapillary atrophy, punched out lesions, a macular disciform lesion or scar in one eye without vitritis. As controls, 66 sex and age matched healthy volunteers were used. Serum samples from both patients and controls were tested for the presence of antibodies against H capsulatum, Toxoplasma gondii, Toxocara canis et cati, Ascaris sp, and for the presence of antigens of Cryptococcus neoformans. Serum samples were also tested for the presence of autoantibodies against retinal or choroidal proteins. To investigate other risk factors, patients and controls were asked to fill in a health and travel related questionnaire. Ten patients with ocular toxoplasmosis were used as a disease control group. RESULTS: None of the patients with presumed ocular histoplasmosis syndrome or controls had circulating antibodies directed against H capsulatum. No risk factors could be identified and no indications for autoimmunity and no evidence for the role of the other infectious agents could be demonstrated. CONCLUSIONS: In a Dutch group of patients fulfilling the criteria of a disease currently named presumed ocular histoplasmosis syndrome, no risk factors or relation with the fungus H capsulatum could be detected. (+info)
Contact lens-induced infection--a new model of Candida albicans keratitis.
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PURPOSE: A model of experimental keratomycosis was established that mimics human disease in which the only fungi present are those that are actively growing within the cornea. METHODS: Dutch-belted rabbits received a subconjunctival injection of triamcinolone acetonide to one eye. One day later the epithelium was removed from the central cornea and a standardized inoculum of Candida albicans blastoconidia was placed on the corneal surface and covered with a contact lens. The lids were closed with a lateral tarsorrhaphy. After 24 hours, the lid sutures and contact lens were removed. Five days later the animals were killed, and their corneas were subjected to separate isolate recovery and histology studies. A group of similarly infected rabbits without corticosteroid injection served as controls. RESULTS: Both groups developed invasive corneal disease. Although isolate recovery was not significantly different from corticosteroid-treated rabbits compared with controls, fungal biomass was increased. Hyphal invasion was limited to the anterior cornea in control eyes, but penetrated deep stroma in most of the corticosteroid-treated rabbits. CONCLUSIONS: Invasive corneal disease can be established with a surface inoculum. Corticosteroid administration increased corneal penetration of hyphae. Quantitative isolate recovery is not a reliable measure of the fungal load within the cornea. (+info)
A study of mycotic keratitis in Mumbai.
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A total of 1010 clinically suspected cases of mycotic keratitis were studied from 1988 to 1996 for evidence of fungal infection and for identification of the aetiologic agents of keratitis in Mumbai. Of these 367 cases were reported positive by microscopy and culture. Seventy nine percent of the cases were between the ages 21 and 50 years. Male patients were more often affected than females. Eighty eight percent of patients were farmers or construction workers and 89.92% of cases gave a definite history of antecedent corneal trauma. A single fungal isolate was obtained in 307 cases and multiple isolates in 20 cases. Mixed isolates of bacteria and fungi were grown in 40 cases. The predominant isolate was Aspergillus species in 219 cases, followed by Candida species (36), Fusarium species (33) and Penicillium species (34). Filamentous fungal isolates from 22 cases remained unidentified. Mycotic keratitis should be suspected in every patient with a corneal lesion and should be ruled out before commencing steroids and antiboitics. (+info)
Microbial decontamination of human donor eyes with povidone-iodine: penetration, toxicity, and effectiveness.
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BACKGROUND/AIMS: Povidone-iodine (PVP -I) is applied for microbial decontamination of human eyes donated for transplantation. Concentrations and immersion times vary greatly. The effectiveness and toxicity of PVP-I were assessed for different decontamination protocols. METHODS: Human donor eyes and corneas were immersed in different concentrations (5-100 mg/ml) of PVP-I for different times (2-30 minutes). The penetration of iodine into the corneal tissue was assessed by x ray microanalysis. Microbial contamination was determined by taking cultures of the limbal areas and storage solutions and by incubation of the corneoscleral buttons in antibiotic-free culture medium. Cytotoxicity of PVP-I for corneal fibroblasts in culture was assessed using the MTT assay. RESULTS: Depending on concentration and immersion time iodine was found to penetrate into the epithelium, Bowman's layer, and stroma in amounts equivalent to 2-40 mg/ml PVP-I. The MTT assay demonstrated that 2.5 mg/ml PVP-I caused total damage to fibroblasts in vitro. Rinsing eyes with tap water and subsequent immersion in PVP-I reduced the rate of contamination from 82 out of 106 to 69 out of 106 and 37 out of 106, respectively. Antibiotics in the storage medium further reduced contamination from about 40% to 3%. Microbial contamination was not reduced by increasing the concentration and immersion times beyond 5 mg/ml PVP-I for 2 minutes. CONCLUSION: Immersion of human donor eyes in 5 mg/ml PVP-I solution for 2 minutes significantly reduces microbial contamination of donor corneas without relevant penetration of iodine into the corneal layers. Higher PVP-I concentrations and longer immersion times do not further reduce contamination, whereas the amount of iodine penetrating the corneal layers is elevated above the level cytotoxic for corneal fibroblasts. In view of this, concentrations above 5 mg/ml of PVP-I and immersion periods over 2 minutes are not recommended for reduction of the contamination rate of donor eyes. (+info)
Fungal corneal ulcers of onion harvesters in southern Taiwan.
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Fungal corneal ulcers related to agriculture has been reported throughout the world, especially in tropical areas. Most of them were sporadic and had histories of ocular trauma or use of topical corticosteroids and topical antibiotics. Five onion harvesters had fungal corneal ulcers during the same harvest period in Southern Taiwan. The authors think that this is the first report of a group occurrence relating to agricultural workers. Although all of the patients improved after medical and surgical management, their vision was greatly decreased. It is suggested that the tropical climate, the harvest procedure, the characteristic monsoon, and lack of eye protection were involved. Therefore, the importance of the eye protection, hygiene education, and improving medical care to reduce the occurrence of fungal corneal ulcer in agriculture workers must be emphasised. (+info)
Mycotic keratitis due to Curvularia senegalensis and in vitro antifungal susceptibilities of Curvularia spp.
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A case of mycotic keratitis due to Curvularia senegalensis is reported. This case represents the third known reported infection caused by this rare species. Fungal hyphae were detected in corneal scrapings, and repeated cultures were positive for this fungi. The patient was presumed cured after a corneal transplant and treatment with itraconazole, but the infection recurred and the patient is waiting for a keratoplasty. The in vitro antifungal susceptibilities of the case strain and another 24 strains belonging to seven species of Curvularia were tested for six antifungal agents. With the exception of flucytosine, and occasionally fluconazole, the other drugs assayed (amphotericin B, miconazole, itraconazole, and ketoconazole) were highly effective in vitro. (+info)
Differences in virulence between two Candida albicans strains in experimental keratitis.
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PURPOSE: To study the differences in disease caused by two wild-type strains of Candida albicans in a model of contact lens-facilitated keratitis in rabbits. METHODS: Two strains, SC5314 and VE175, were examined. Standardized inocula were placed on the debrided corneal surface of one eye in Dutch belted rabbits and covered with a contact lens. A temporary tarsorrhaphy was opened after 24 hours with removal of the contact lens. Six days later, corneas were photographed and animals killed. Corneas were bisected with one half for quantitative isolate recovery and the other for stromal penetration by hyphae. RESULTS: Strain SC5314 was significantly more virulent. The mean hyphal penetration into the cornea was 24.4% +/- 8.5% of the corneal thickness, and in three of six corneas hyphae penetrated through the entire cornea. In contrast, for VE175, the mean hyphal penetration was 2.6% +/- 1.2%. The difference between these two strains was statistically significant (P = 0.0297). Hyphae did not penetrate into the deep layers of the cornea in any of the six rabbits infected with VE175. The grading of clinical disease was consistent with histology, in that strain SC5314 caused more severe infection than VE175 and the difference was statistically significant (P = 0.0048). There was no difference in isolate recovery. CONCLUSIONS: Wild-type strains of C. albicans can differ significantly in virulence as measured by depth of fungal invasion into corneas and clinical evaluation of infection. Further characterization of the intrinsic genetic differences between such strains may help identify factors responsible for fungal virulence. (+info)
PCR-RFLP-mediated detection and speciation of bacterial species causing endophthalmitis.
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PURPOSE: To determine the usefulness of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in the identification and speciation of bacteria causing endophthalmitis. METHODS: PCR-RFLP was performed on 53 strains of 14 bacterial species (eight Gram positive and five Gram negative) collected from both keratitis and endophthalmitis patients. Two pairs of oligonucleotide primers based on the 16S rDNA gene were used to PCR-amplify 1.2- and 1.0-kb fragments of bacterial genomic DNA. RFLPs within the PCR product were used to speciate the organisms. RESULTS: The sensitivity of the nested PCR amplification reaction was one organism. All bacteria tested could be identified and speciated using RFLP analysis except for Escherichia coli and Serratia marcescens, which could not be interdifferentiated using RFLP. Molecular analysis of two vitreous samples from two eyes with typical signs of bacterial endophthalmitis confirmed the presence of E. coli in the vitreous from a culture-positive case with E. coli endophthalmitis and revealed the presence of Staphylococcus epidermidis in the vitreous of a culture-negative case. CONCLUSIONS: It is expected that this technique will provide a useful laboratory tool for future microbiologic diagnosis of patients presenting with endophthalmitis, especially for those eyes that prove culture negative. (+info)