Intrahyphal hyphae in corneal tissue from a case of keratitis due to<i>Lasiodioplodia theobromae</i>

Thomas, Philip A.; Garrison, Robert G.; Jansen, T.

doi:10.1080/02681219180000381

Cited by 23 publications

(13 citation statements)

References 14 publications

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“…This permits fungi to survive in the presence of anti-fungal drugs and resist anti-microbial therapy. The same intrahyphal hyphae or hypha-in-hypha and thickened fungal cell walls are seen in corneal tissues infected with L. theobromae and in corneas infected with F. solani keratitis treated earlier with corticosteroids, as seen in the presence of antifungal drugs [94,193]. This suggests that these morphological alterations may allow fungi to evade host defenses and present a barrier against antifungal drugs [77] demonstrated the role of EFG1-regulated SAP6 gene of C. albicans which encodes for a unique secreted aspartyl proteinase.…”

Section: Invasiveness and Morphogenesismentioning

confidence: 81%

Pathogenesis of microbial keratitis

Lakhundi

Siddiqui

Khan

2017

Microbial Pathogenesis

181

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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Section: Invasiveness and Morphogenesismentioning

confidence: 81%

Pathogenesis of microbial keratitis

Lakhundi

Siddiqui

Khan

2017

Microbial Pathogenesis

181

121

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“…1 It has been hypothesised that rapid progression of mycotic keratitis in the early phases is mainly by agent factors, such as a large fungal inoculum and penetration deep into the corneal stroma, while progression in the later phases involves a combination of agent and host factors and resistance to antifungals. 17 Invasiveness of fungi in corneal tissue may be aided by formation of intrahyphal hyphae, 57,58 or by liberation of fungal proteinases 59 or toxins. 60 Progression of mycotic keratitis may be augmented by the activation of resident corneal cells or inflammatory cells, particularly polymorphonuclear leucocytes, which release proteinases of different molecular weights, resulting in extensive degradation of the corneal tissue matrix.…”

Section: Eyementioning

confidence: 99%

Fungal infections of the cornea

Thomas

2003

Eye

384

292

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“…This organism was initially reported as a cause of human keratitis in two patients in India (305). Subsequently, reports from the southern United States, other parts of India, Sri Lanka, and other countries have confirmed that this fungus is pathogenic in the human cornea (37,117,216,318,356,392,393); brown, highly bulged, septate hyphae are seen in infected corneal tissue. This fungus causes severe keratitis in experimental animals (305,318) and in humans (37,318,392,393).…”

Section: Morphology In Culturementioning

confidence: 99%

“…The presence of "intrahyphal hyphae" or "hypha-in-hypha," and thickened fungal cell walls (Table 9) may reflect such morphogenesis occurring in fungi invading corneal tissue; these morphological alterations may constitute a barrier against antifungal drugs or host defenses (392,393) or may be a virulence factor for fungi in corneas where the defense mechanisms have been compromised by the application of corticosteroids (190). Rigorous experimental and other studies are required to elucidate these aspects.…”

Section: Putative Agent Factors In the Pathogenesis Of Mycotic Keratitismentioning

confidence: 99%

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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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Intrahyphal hyphae in corneal tissue from a case of keratitis due toLasiodioplodia theobromae

Cited by 23 publications

References 14 publications

Pathogenesis of microbial keratitis

Pathogenesis of microbial keratitis

Fungal infections of the cornea

Current Perspectives on Ophthalmic Mycoses

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