Challenges in the diagnosis and management of atypical fungal keratitis during the COVID-19 pandemic: a case series

Abstract

Fungal keratitis is a time-sensitive ocular infection that often requires a high index of suspicion followed by intensive medical/surgical interventions to achieve a successful clinical outcome. COVID-19 pandemic-related restrictions, necessitated the modification of conventional protocols and guidelines associated with the treatment of keratomycosis. We report four cases of atypical fungal keratitis with poorly differentiated clinical characteristics. The challenges faced during their management were (1) the dilemma of clinically differentiating fungal (Scedosporium and Purpureocillium lilacinum) and bacterial keratitis; (2) treatment of Scedosporium and Trichosporon keratitis with natamycin monotherapy; (3) mixed infection of Candida albicans and Aureobasidium pullulans and continuing medications before rescraping the corneal ulcer against the recommended treatment guidelines; (4) phenotypic identification and differentiation among morphologically resembling fungi; and (5) decision making arising out of disparities between KOH and fungal culture results. Three patients responded well to conservative treatments. The fourth patient underwent therapeutic keratoplasty but was lost to follow-up due to travel-related pandemic restrictions. This case series seeks to broaden the clinician's knowledge of rare and emerging moulds as presumptive aetiologies of keratomycosis. It also intends to emphasize the significance of early microbiological investigations, (direct microscopy and culture), in resource-limited settings, for initiating empirical treatment for a better visual prognosis.

Keywords: Atypical fungal keratitis; Aureobasidium; COVID-19; Purpureocillium; Scedosporium; Trichosporon.

Fig. 1.

(a) Healed thin corneal scar near the pupillary area (case 2). (b) Anterior segment-optical coherence tomography (AS OCT) of case 2 showing small thin scar in the superficial corneal stroma.

Fig. 2.

(a) Deep corneal stroma infiltrate and hypopyon (case 3). (b) Healed FK with thinning and leucomatous opacity (case 3). (c) Healed FK, fluorescein staining under cobalt blue filter (case 3). (d) AS OCT showing corneal thinning deep stromal scarring (case 3).

Fig. 3.

a,b Colony morphology and LPCB tease mount preparation (magnification 100x) of Scedosporium species complex.

Fig. 4.

a,b Colony morphology and Gram stain (magnification 100x) of Trichosporon asahii.

Fig. 5.

a,b Colony morphology and LPCB tease mount preparation (magnification 100 x) of Aureobasidium pullulans c, d Colony morphology and Gram stain (magnification 100 x) of Candida albicans.

Fig. 6.

a,b Colony morphology and LPCB tease mount preparation (magnification 100x) of Purpureocillium lilacinum.