Assessment of in vitro dynamics of pathogenic Acanthamoeba strains originating from contact lens wearers with infectious keratitis

Recently, incidents of Acanthamoeba keratitis, the vision-threatening eye disease, are reported with increasing frequency worldwide, particularly in contact lens wearers. In our study, the retrospective assessment of in vitro dynamics of subsequent pathogenic Acanthamoeba isolates cultured at 24°C, detected in Polish contact lens wearers with keratitis is presented and results compared with those of environmental A. castellanii Neff strain. There were delayed the proper diagnosis that influenced prolonged and severe course of this eye disease and treatment difficulties. The corneal material was examined directly to visualize developmental amoeba stages for diagnose verification, microbiologically tested for the specific identification of bacteriae and fungi, and in vitro grown in culture medium in temperature 24°C. Among twenty-six keratitis incidents analyzed, eleven were cases of Acanthamoeba keratitis; in the six of them, Acanthamoeba strains and concomitant bacterial and/or fungal infectious agents were detected. In vitro assays showed variability in population density of several clinical strains in the exponential growth phase expressed in various range of overall amoeba number and different proportion between trophozoites and cysts. The clear influence of temperature on the in vitro cultivation of the amoebae was observed: statistically significant lower population dynamics was revealed by most of pathogenic clinical isolates in comparison with those showed by environmental strain. The in vitro monitoring of dynamics of Acanthamoeba strains isolated from infected eyes may be helpful for diagnostics verification, especially in mixed infectious keratitis.