In an effort to characterize, on the molecular scale, the Acanthamoeba initially isolated from the cornea of an amoebic keratitis patient associated with overnight-wear orthokeratology lens in Korea, we conducted mitochondrial DNA restriction fragment length polymorphism, 18S rDNA sequencing, and drug sensitivity analyses on the isolate (KA/PE1). The patient was treated with polyhexamethylene biguanide, chlorhexidine and oral itraconazole, which resulted in resolution of the patient's ocular inflammation. The majority of the molecular characteristics of the KA/PE1 were determined to be identical, or quite similar, to those of A. castellanii Ma strain, which had been isolated also from amoebic keratitis. The risk of Acanthamoeba keratitis as a potential complication of overnight orthokeratology is briefly discussed.
*Sequence Analysis, DNA ; RNA, Ribosomal, 18S/genetics ; Polymorphism, Restriction Fragment Length ; Parasitic Sensitivity Tests ; Myopia/therapy ; Itraconazole/administration & dosage ; Humans ; Female ; Disinfectants/administration & dosage ; DNA, Ribosomal/analysis ; DNA, Protozoan/analysis ; DNA, Mitochondrial/analysis ; Contact Lenses/*adverse effects ; Chlorhexidine/administration & dosage ; Biguanides/administration & dosage ; Astigmatism/therapy ; Antiprotozoal Agents/administration & dosage ; Animals ; Adolescent ; Acanthamoeba Keratitis/drug therapy/*parasitology ; Acanthamoeba/classification/*genetics/*isolation & purification

Three Acanthamoeba isolates (KA/E9, KA/E17, and KA/E23) from patients with keratitis were identified as Acanthamoeba triangularis by analysis of their molecular characteristics, a species not previously recognized to be a corneal pathogen. Epidemiologic significance of A. triangularis as a keratopathogen in Korea has been discussed. Morphologic features of Acanthamoeba cysts were examined under a microscope with differential interference contrast (DIC) optics. Mitochondrial DNA (mtDNA) of the ocular isolates KA/E9, KA/E17, and KA/E23 were digested with restriction enzymes, and the restriction patterns were compared with those of reference strains. Complete nuclear 18S and mitochondrial (mt) 16S rDNA sequences were subjected to phylogenetic analysis and species identification. mtDNA RFLP of 3 isolates showed very similar patterns to those of SH621, the type strain of A. triangularis. 16S and 18S rDNA sequence analysis confirmed 3 isolates to be A. triangularis. 18S rDNA sequence differences of the isolates were 1.3% to 1.6% and those of 16S rDNA, 0.4% to 0.9% from A. triangularis SH621. To the best of our knowledge, this is the first report, confirmed by 18S and 16S rDNA sequence analysis, of keratitis caused by A. triangularis of which the type strain was isolated from human feces. Six isolates of A. triangularis had been reported from contaminated contact lens cases in southeastern Korea.
Acanthamoeba/classification/genetics/isolation & purification ; Acanthamoeba Keratitis/*drug therapy/*parasitology ; Adolescent ; Adult ; Animals ; Antiprotozoal Agents/therapeutic use ; Biguanides/therapeutic use ; DNA, Mitochondrial/genetics ; DNA, Protozoan/genetics ; Female ; Humans ; Male ; Phylogeny ; Polymorphism, Restriction Fragment Length ; RNA, Ribosomal, 16S/genetics ; RNA, Ribosomal, 18S/genetics