Commercial eye drops triggers necrotic effect in Acanthamoeba sp.

Abstract

Eye infection due to microbial infection is hard to treat and painful. Two types of eye drops that are commonly used to relieve eye pain offered by pharmacists have been tested in this study namely solution A (containing tetrahydrozoline hydrochloride) and solution B (containing gentamicin and dexamethasone). The efficacy and the activities of these eye drops were tested on Acanthamoeba sp. (a clinical isolate from an Acanthamoeba keratitis patient) to study the cytotoxicity effects of the solutions on the Acanthamoeba. The Acanthamoeba were exposed to solution A and B for 24 hr and cell viability was assessed using MTT assays, morphological changes using the light microscope and through acridine orange and propidium iodide (AO/PI) staining for cytoplasmic biochemical activities. The IC50 value for Acanthamoeba cell viability was 45.1% and 20.3% for solutions A and B respectively. Morphological observation shows the inhibition of acanthapodia formation on the surface of the cells. Solution A and B-treated Acanthamoeba appeared in the red color of the cytoplasm upon staining with AO/PI indicating a necrotic mode of cell death. This is due to loss of membrane integrity of Acanthamoeba cell membrane after exposed to solution A and B at their IC50 value. It is shown that solutions A and B can cause cell death in trophozoite of Acanthamoeba cells at moderate IC50 value. Unfortunately, the necrosis mode of cell death is not a preferable type of cell death for treating Acanthamoeba infection. Therefore, it can be concluded that solutions A and B are not suitable to treat eye infected with Acanthamoeba sp. as it does not promise absolute healing as the solution concentration needed is quite high and the cell death mechanism is necrosis.