Recognition and chemotherapy of oculomycosis

Abstract

Summary Oculomycosis may be divided into the orbital infections of phycomycosis of Aspergillus and other species and the infections of the globe. The latter comprise endogenous, post-surgical or traumatic intra-ocular infections and direct infections of the cornea: these are the commonest form of oculomycosis. They are not easy to differentiate from other, more common causes of septic infection of the eye. The early recognition of fungal infections of the eye thus rests on maintaining an efficient service for all septic infections of the eye. Candida albicans and other dimorphic fungal infections are best treated with flucytosine combined with either polyenes such as amphotericin B and natamycin or combined with imidazoles such as clotrimazole or miconazole. Aspergillus spp. account for about 50% of the cases of filamentous fungal infection of the cornea but more than 100 species of varying pathogenicity and drug sensitivity have been implicated. Econazole, clotrimazole or miconazole combined with thiabendazole are recommended for Aspergillus spp. Econazole, thiabendazole or miconazole combined with flucytosine for Cladosporium sp. For Fusarium solani and other species econazole is the best drug but some isolates are sensitive to thiabendazole or other imidazoles. Alternatively, filamentous fungal infections may be treated with natamycin which has a broad spectrum of activity; but does not penetrate well and, like other polyenes, should not be combined with imidazole antifungal chemotherapy because of antagonistic drug interaction. Overall, econazole emerges as the most widely acting drug; but successful results are dependent on rather complex investigation with intensive and protracted care that can best be provided in a few centres of referral.

Fungal infections of the cornea

“…10,17,36,44 If hyphae are definitely seen by microscopy, topical natamycin (5%) is the drug of choice (0.15% amphotericin B is another option). 42,45 Econazole (1%) was recommended by some workers in the 1970s, 16,46 but there are no recent reports about the use of this compound as first-line therapy for mycotic keratitis. If yeasts or pseudohyphae are seen on microscopy, topical 0.15% amphotericin B, 10,44 fluconazole 2%, 47 natamycin 5%, 10 other azoles at 1% in arachis oil, or 1% flucytosine eye drops can be used.…”

“…13 Topical therapy is usually applied hourly around the clock for several days and the frequency of application is then gradually reduced; 42 'topical saturation therapy' has also been advocated. 46 Some form of systemic therapy (oral azoles, intravenous miconazole) is usually included for severe keratitis. 10,36,44,[48][49][50] Topical 2% fluconazole was found efficacious in six Indian patients with microscopy-and culture-proven Candida keratitis with deep lesions; 47 three of these patients had not responded to topical natamycin, while the other three had not responded to topical miconazole.…”

Keratomycosis caused by Dichotomophthoropsis nymphaearum

“…The isolate of D. nymphaearum was sensitive to both econazole and miconazole. Econazole has the best activity of the imidazoles against ocular fungi [5] and unlike other imidazoles shows good activity against Fusarium spp. It is however somewhat irritant to the corneal epithelium.…”

Mycotic keratitis: Susceptibility to antiseptic agents

“…Pyrimidines such as 5-fluorocytosine are only effective against yeasts. The azoles have been widely used, especially clotrimazole, miconazole and econazole, the latter appearing to have the broadest spectrum [7]. Fluconazole penetrates the eye well [1].…”