Genotyping of Acanthamoeba isolates and clinical characteristics of patients with Acanthamoeba keratitis in China.

Acanthamoeba keratitis (AK) is a sight-threatening corneal infection, the epidemiology of which is related to the specific genotype of Acanthamoeba. In this study, the genotypes of 14 Acanthamoeba isolates, each from a patient with AK, were identified according to the highly variable DF3 region in the 18S rRNA gene at Shandong Eye Institute, PR China, from 2000 to 2009, and the clinical characteristics of these patients were analysed. All 14 amoebae were genotype T4, representing nine different DF3 sequence types, seven of which were newly identified. Cornea infestation was the main risk factor for these 14 AK patients. Amoebic cysts could be detected in all corneal scrapes. Corneal ulcers were located mainly at the corneal centre, accompanied by eye pain, and some appeared with a Wessely ring. Surgery was carried out on all patients. Acanthamoeba genotypes T4/26 and T4/27 were found to cause a more severe keratitis, whilst the others showed no significant differences in clinical characteristics. In conclusion, the majority of the keratitis-causing Acanthamoeba isolates were genotype T4, with Acanthamoeba genotypes T4/26 and T4/27 from PR China causing a more severe keratitis.