Confirmatory Evidence from 18S rRNA Gene Analysis for In Vivo Development of Propamidine Resistance in a Temporal Series of Acanthamoeba Ocular Isolates from a Patient

DNA sequences of three 18S rRNA gene alleles present in trophozoites obtained before and after therapy for Acanthamoeba keratitis substantiate a previous report that the infection was due to a single Acanthamoeba strain. Thus, the possibility that propamidine resistance which developed during therapy was due to a mixed infection was ruled out.