Acanthamoeba Species Keratitis in a Soft Contact Lens Wearer Molecularly Linked to Well Water

Abstract

An otherwise-healthy 14-year-old female soft contact lens wearer, who lived in a rural area where the tap water source for the home was a well, presented to a community hospital with a four-week history of progressive redness, swelling and blurred vision of her left eye despite treatment with topical neomycin and corticosteroids. A dendritiform corneal epithelial lesion, corneal edema and inflammation in the anterior chamber were noted on initial examination, and treatment for herpes simplex keratouveitis with oral valacyclovir and topical trifluridine 1% was initiated. There was no clinical improvement, and six weeks after the onset of symptoms she was referred to a corneal specialist for evaluation and further management. The patient's visual acuity was 20/80 and her corneal sensation was intact; slit-lamp examination revealed diffuse corneal edema, areas of punctate epithelial staining, poorly defined subepithelial and anterior stromal infiltrates, a partial ring infiltrate and 2+ cell and flare in the anterior chamber (Figure 1). The patient underwent corneal debridement, and scrapings were sent for viral, bacterial and Acanthameoba culture. She was admitted to the hospital, and polyhexamethalene biguanide 0.02% and diamidine propamidine isothianate eye drops were added to antiviral therapy and topical neomycin. Over the next few days, her visual acuity decreased to hand movement only, the corneal edema intensified, and midstromal peripheral vascularization developed. Her corneal epithelium healed promptly following debridement. Treatment with oral itraconazole, topical chlorhexidine 0.02% and topical ciprofloxacin were added after Acanthameoba species were isolated from corneal scrapings. Over the next few months, the patient improved markedly (her left visual acuity was 20/50) despite significant corneal vascularization and persisting central stromal opacity.Clinical samples, including corneal scrapings, contact lenses, contact lens solution, tap water and well water, were inoculated directly onto non-nutrient agar with Escherichia coli overlay (1), as well as sheep's blood agar, MacConkey agar and chocolate agar. The non-nutrient agar with E coli overlay was incubated at room temperature. The agar surface of the plates was examined daily with an inverted microscope at 10× magnification. On day 5 after planting, the plates inoculated by corneal scrapings were positive for both the cyst (Figure 2) and trophozoite forms of Acanthamoeba species. In addition, Serratia marcescens and Stenotrophomonas maltophilia were isolated from corneal scrapings that were inoculated onto sheep's blood agar, MacConkey agar and chocolate agar. Environmental samples consisting of well water and tap water from the patient's home, in addition to samples from the contact lens case, were also positive for Acanthamoeba species. Acanthamoeba species isolates were forwarded to the Ohio State University Department of Molecular Genetics (Columbus, Ohio, USA), where molecular epidemiological analysis was undertaken. This consisted of amp...

Acanthamoeba Keratitis among Rigid Gas Permeable Contact Lens Wearers in the United States, 2005 through 2011

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Microbial Bioburden of Orthokeratology and Hydrogel Contact Lenses and Storage Cases Using a Hydrogen-Peroxide Disinfecting System

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