Abstract
BackgroundAcanthamoeba spp. keratitis is a devastating disease that can potentially result in threatening the sight of the affected eye. Ineffective lens-disinfecting systems and contaminated contact lens storage cases have been recognized as the main risk factors for the infection.ObjectivesThe present study aimed to evaluate the efficacy of nine different commercially available contact lens solutions in the Egyptian market against Acanthamoeba spp. trophozoites and 2-week-old cysts.Materials and methodsNine solutions were tested: eight multipurpose solutions (MPS) and one one-step hydrogen peroxide solution. Acanthamoeba spp. was isolated from a keratitic patient, cultivated on 1.5% non-nutrient agar (NNA), harvested, adjusted in two final concentrations of 5 × 10 3 and 5 × 10 5 trophozoites and cysts, and then incubated with the contact lens solution. The efficacy was tested at intervals of 2, 4, 6, 8, 10, and 24 h. Experiments were performed in triplicate. The viability was confirmed by reinoculation onto NNA seeded with Escherichia coli (NNA-E. coli).ResultsMost of the tested solutions showed significant trophzoiticidal activity, whereas all of the tested solutions failed to eliminate the 2-week-old cysts completely. The one-step hydrogen peroxide system failed neutralization within the minimum manufacturer's disinfecting time as it killed all the cysts of 5 × 10 3 concentration after 10 h of soaking instead of 6 h; if used for this prolonged time, it could be hazardous to the users' eye. One of the MPS had high trophozoiticidal activity, but with an unknown recorded disinfectant, which could turn out to be of a toxic concentration or constitution.ConclusionAdjustment of the appropriate concentration of the disinfectant, the adequate exposure time, or even the development of new contact lens-disinfecting systems by manufacturers is needed to prevent Acanthamoeba spp. keratitis (AK). A MPS that fails to eradicate trophozoites or cysts within the minimum manufacturer's disinfecting time or one with an unknown recorded disinfectant should be avoided.
Published Version
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