Drug-Resistant Severe Acanthamoeba Keratitis Caused by Rare T5 Acanthamoeba Genotype

OBJECTIVE: To describe a case of severe and drug-resistant Acanthamoeba keratitis in a contact lens wearer caused by atypical T5 Acanthamoeba genotype (Acanthamoeba lenticulata). METHODS: Report of a case, Acanthamoeba DNA amplification and sequencing. RESULTS: A 61-year-old patient was referred to our clinic with a 2-week history of keratitis. Acanthamoeba keratitis (AK) was diagnosed using confocal microscopy and corneal scraping culture. Using polymerase chain reaction (PCR) and DNA sequencing, the organism was classified as a T5 genotype (A. lenticulata). The keratitis continued to progress despite topical antiamoebic therapy and ultimately led to enucleation of the affected eye. CONCLUSIONS: T5 genotype Acanthamoeba can cause severe AK. Atypical Acanthamoeba genotypes could be associated with worse prognosis and resistance to therapy.