An in-vitro study of the sterol content and toxin production of Fusarium isolates from mycotic keratitis

Raza, Sherow; Mallet, A. I.; Howell, S. A.; Thomas, Philip A.

doi:10.1099/00222615-41-3-204

Cited by 19 publications

(12 citation statements)

References 18 publications

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“…In harmony with our results, Raza et al . [24] found that isolates of Fusarium species from 18 pateints with keratomycosis could produce mycotoxins in vitro . Of these isolates, 13 produced nivalenol, 6 produced deoxynivalenol, 9 gave T-2 toxin, and 2 showed the presence of diacetoxyscirpenol at different intervals.…”

Section: Discussionmentioning

confidence: 99%

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

Gharamah

Moharram

Ismail

et al. 2014

Indian J Ophthalmol

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Purpose:This work was conducted to study the ability of bacterial and fungal isolates from keratitis cases in Upper Egypt to produce enzymes, toxins, and to test the isolated fungal species sensitivity to some therapeutic agents.Materials and Methods:One hundred and fifteen patients clinically diagnosed to have microbial keratitis were investigated. From these cases, 37 bacterial isolates and 25 fungal isolates were screened for their ability to produce extra-cellular enzymes in solid media. In addition, the ability of fungal isolates to produce mycotoxins and their sensitivity to 4 antifungal agents were tested.Results:Protease, lipase, hemolysins, urease, phosphatase, and catalase were detected respectively in 48.65%, 37.84%, 59.46%, 43.24%, 67.57%, and 100% out of 37 bacterial isolates tested. Out of 25 fungal isolates tested during the present study, 80% were positive for protease, 84% for lipase and urease, 28% for blood hemolysis, and 100% for phosphatase and catalase enzymes. Thirteen fungal isolates were able to produce detectable amounts of 7 mycotoxins in culture medium (aflatoxins (B1, B2, G1, and G2), sterigmatocystin, fumagillin, diacetoxyscirpenol, zearalenone, T-2 toxin, and trichodermin). Among the antifungal agents tested in this study, terbinafine showed the highest effect against most isolates in vitro.Conclusion:In conclusion, the ability of bacterial and fungal isolates to produce extracellular enzymes and toxins may be aid in the invasion and destruction of eye tissues, which, in turn, lead to vision loss.

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Section: Discussionmentioning

confidence: 99%

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

Gharamah

Moharram

Ismail

et al. 2014

Indian J Ophthalmol

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“…are known to cause myelosuppression through toxin production (263), but little is known about whether Fusarium toxins such as nivalenol, T-2 toxin, deoxynivalenol, diacetoxyscirpenol and fusaric acid contribute to the pathogenesis of mycotic keratitis ( Table 9). The results of two studies (316,383) suggest that these factors do not make any such contribution, but further investigation is required.…”

Section: Putative Agent Factors In the Pathogenesis Of Mycotic Keratitismentioning

confidence: 98%

Current Perspectives on Ophthalmic Mycoses

2003

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Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal therapy is instituted as soon as the diagnosis is made. Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic mycoses. Topical natamycin is usually the first choice for filamentous fungal keratitis, and topical amphotericin B is the first choice for yeast keratitis. Increasingly, the triazoles itraconazole and fluconazole are being evaluated as therapeutic options in ophthalmic mycoses. Medical therapy alone does not usually suffice for invasive fungal orbital infections, scleritis, and keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical debridement is essential in orbital infections, while various surgical procedures may be required for other infections not responding to medical therapy. Corticosteroids are contraindicated in most ophthalmic mycoses; therefore, other methods are being sought to control inflammatory tissue damage. Fungal infections following ophthalmic surgical procedures, in patients with AIDS, and due to use of various ocular biomaterials are unique subsets of ophthalmic mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors

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“…Several toxins produced by Fusarium spp. include nivalenol, T-2 toxin, deoxynivalenol, diacetoxyscirpenol and fusaric acid [157] studied the relationship of toxin production with the severity of disease and concluded that toxin production in vitro did not relate to the clinical presentation of severity of keratitis and the outcome of the treatment. The toxic effects of aflatoxins on the cornea of chicks has been established [86].…”

Section: Toxigenicitymentioning

confidence: 99%

Pathogenesis of microbial keratitis

Lakhundi

Siddiqui

Khan

2017

Microbial Pathogenesis

167

121

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Microbial keratitis is a sight-threatening ocular infection caused by bacteria, fungi, and protist pathogens. Epithelial defects and injuries are key predisposing factors making the eye susceptible to corneal pathogens. Among bacterial pathogens, the most common agents responsible for keratitis include Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumonia and Serratia species. Fungal agents of corneal infections include both filamentous as well as yeast, including Fusarium, Aspergillus, Phaeohyphomycetes, Curvularia, Paecilomyces, Scedosporium and Candida species, while in protists, Acanthamoeba spp. are responsible for causing ocular disease. Clinical features include redness, pain, tearing, blur vision and inflammation but symptoms vary depending on the causative agent. The underlying molecular mechanisms associated with microbial pathogenesis include virulence factors as well as the host factors that aid in the progression of keratitis, resulting in damage to the ocular tissue. The treatment therefore should focus not only on the elimination of the culprit but also on the neutralization of virulence factors to minimize the damage, in addition to repairing the damaged tissue. A complete understanding of the pathogenesis of microbial keratitis will lead to the rational development of therapeutic interventions. This is a timely review of our current understanding of the advances made in this field in a comprehensible manner. Coupled with the recently available genome sequence information and high throughput genomics technology, and the availability of innovative approaches, this will stimulate interest in this field.

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An in-vitro study of the sterol content and toxin production of Fusarium isolates from mycotic keratitis

Cited by 19 publications

References 18 publications

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

Current Perspectives on Ophthalmic Mycoses

Pathogenesis of microbial keratitis

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