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Thread: Fungal keratitis capsule

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    Default Fungal keratitis capsule

    Fungal keratitis capsule



    ✍️ rare.

    ✍️ usually seen with trauma with organic material or where there is underlying susceptibility such as tissue devitalization or immunosuppression (including topical corticosteroid use).

    ✍️ Candida, Fusarium, and Aspergillus spp. are the most common infectious agents.

    Risk factors

    ✍️ trauma (including LASIK)

    ✍️ immunosuppression

    ☝️ topical corticosteroids
    ☝️ alcoholism
    ☝️ diabetes
    ☝️ systemic immunosuppression

    ✍️ ocular surface disease

    ☝️ dry eye
    ☝️neurotrophic cornea
    ☝️hot humid climate
    ☝️contamination with organic matter (agricultural work, gardening, etc.)

    Fungal keratitis capsule attachment.php?attachmentid=3462&d=1512900165

    Yeast infection

    ✍️ Candida species
    ✍️ Frequently associated with immunosuppression
    ✍️ those who have a compromised ocular surface

    Filamentary fungal infection

    ✍️ Fusarium and Aspergillus species.

    Clinical features

    General

    ✍️ variable presentation
    ✍️ onset ranging from insidious to rapid
    ✍️ symptoms range from none to pain, photophobia, tearing, and dropped VA.

    Yeast infection

    ✍️ insidious or rapid
    ✍️ often localized with button appearance expanding stromal infiltrate with relatively small epithelial ulceration.

    Filamentary fungal infection

    ✍️ usually insidious.
    ✍️ Early
    ☝️ may be asymptomatic
    ☝️ intact epithelium
    ☝️ minimal corneal stromal infiltrate
    ☝️ mild AC in ammation.

    ✍️ Later

    ☝️ satellite lesions
    ☝️ feathery branching infiltrate
    ☝️ immune ring.

    ✍️ In severe infection

    ☝️ ulceration
    ☝️ involvement of deeper corneal layers and Descemet’s membrane
    ☝️ white plaque on the endothelium
    ☝️ severe AC inflammation (hypopyon).

    Complications

    ✍️ limbal and scleral extension
    ✍️ corneal perforation
    ✍️ endophthalmitis
    ✍️ 2ry bacterial infections (infectious crystalline keratopathy)

     NB In late infection, these distinctive patterns may be lost, and the clinical appearance may resemble an advanced bacterial keratitis.

    Investigation

    ✍️Perform early and adequate corneal scrapes

    ✍️ Stains

    ☝️ gram (stains fungal walls)
    ☝️ giemsa (stains walls and cytoplasm)
    ☝️ grocott’s methenamine silver (GMS) stain, periodic acid–Schi (PAS) stain, and Calco uor white may also be used.

    ✍️ Culture

    ☝️ Sabouraud dextrose agar (for most fungi)
    ☝️ blood agar (for Fusarium)

    ✍️ If strong clinical suspicion, but negative investigations consider

    ☝️ confocal microscopy
    ☝️ corneal biopsy for histopathology
    ☝️ PCR for fungal DNA.

    Fungal keratitis treatment

    ✍️ Effective eradication of fungi is frequently difficult because of the deeply invasive nature of the infectious process.

    ✍️ Identification of the organism must be a priority so as to ensure the optimal choice of therapy.

    ✍️ Admit.

    ✍️ Intensive topical broad-spectrum antifungal agents

    ☝️ non-preserved clotrimazole 1%
    ☝️ natamycin 5% (preserved only)
    ☝️ voriconazole 1%
    ☝️ dose hourly day and night for the first 72h
    ☝️ voriconazole is the preferred agent for suspected or proven candidal infection and natamycin for filamentary fungal infection.
    ☝️ For severe or unresponsive disease, add a second agent (preservative-free amphotericin 0.15% hourly day and night for first 24h, then reducing to day only).
    ☝️ Avoid corticosteroids (reduce or stop them if already on them) but may cautiously be used during healing phase
    ☝️ Oral analgesia and cycloplegia (preservative-free cyclopentolate 1% 3×/d).

    ✍️ Systemic treatment in fungal keratitis

    ☝️ consider oral fluconazole (50–100mg 1×/d for 7–14d) which is effective against Candida and Aspergillus.
    ☝️ In resistant cases or where Aspergillus has been identified: consider voriconazole (PO 400mg 2×/d for two doses, then 200mg 2×/d, but can increase to 300mg 2×/d OR (IV 6mg/kg 2×/d for two doses, then 4mg/kg 2×/d).

    ☝️ An alternative for invasive yeast infections is IV flucytosine (50mg/kg 4×/d then adjust as per plasma level monitored

    ☝️ Consider systemic antifungal treatment with

    • Severe disease
    • deep stromal lesions
    • threatened perforation
    • endophthalmitis
    • All immunocompromised patients.
    • Topical treatment should be continued.

    ☝️ Liaise with a microbiologist for advice drug selection, dosing, and monitoring.

    ☝️ Systemic antifungals are associated with significant side effects

    • renal dysfunction (voriconazole)
    • hepatotoxicity ( fluconazole, voriconazole)
    • blood disorders ( flucytosine, voriconazole).

    ☝️ Monitoring should include FBC, U+E, and LFT prior to starting treatment and at least weekly during treatment.

    ☝️ dosing may need to be reduced in the presence of renal dysfunction

    ✍️ Taper treatment, according to clinical improvement.

    ✍️ Relapse is common and may signify incomplete sterilization or reactivation.

    ✍️ Treatment is prolonged (12wk).

    ✍️ In the healing phase, topical corticosteroids (preservative-free dexamethasone 0.1% 1×/d) are sometimes used but this should be at the direction of a corneal specialist and carefully monitored.

    ✍️ Consider PK

    ☝️ progressive disease (to remove fungus or prevent perforation)
    ☝️ in the quiet, but visually compromised, eye.

    
    Antifungal agents and mode of action


    ✍️ Polyene

    ☝️Destabilize cell wall
    ☝️ Natamycin, amphotericin


    ✍️ Imidazole

    ☝️ Destabilize cell wall
    ☝️ Clotrimazole, econazole, ketoconazole, miconazole

    ✍️ Triazole

    ☝️ Destabilize cell wall
    ☝️ Itraconazole, voriconazole, fluconazole


    ✍️ Pyrimidine

    ☝️ Cytotoxic
    ☝️ Flucytosine











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