Morphological and Physiological Features of Selected Acanthamoeba Strains: Clues to Opportunistic Pathogenicity

Acanthamoeba are common in all environments and are the cause of Acanthamoeba keratitis. Acanthamoeba keratitis is a sight threatening infection of the cornea commonly found in association with contact lens wear. Acanthamoeba isolates tested grew at temperatures up to 35°C. They were also shown to be capable of growth at low oxygen conditions. Comparison between known pathogenic isolates and environmental isolates showed no clear difference in ability to grow in these conditions. Five isolates, three pathogenic, NSU05023, NSU05012, and NSU06001; and two environmental ones BP and MS26 grew faster to 400 trophozoites in low oxygen conditions than in ambient air. This ability would allow the isolates to grow between the contact lens and the cornea. Five contact lens multi-purpose solutions (Clear Care®, Opti-Free®, Complete®, Renu®, and Aquify®) were tested against four isolates; two pathogenic isolates NSU06004 and P120 and two environmental isolates HK17P191 and FLA22. Results showed that the hydrogen peroxide solution (Clear Care®) was more effective against all strains at 78.75% and the remaining four MPS solutions were below 35%. Acanthamoeba are very common in all environments and are capable of infecting the eye. The currently available contact lens disinfecting solutions are not very effective in preventing Acanthamoeba growth