Abstract
Allovahlkampfia
spelaea (
A. spelaea
) is a free-living amoeba, proved to cause
Acanthamoeba-
like keratitis with quite difficult treatment. This study aimed to evaluate the amoebicidal effect of
Allium cepa
(
A. cepa
) on
A. spelaea
trophozoites and cysts both in vitro and in vivo using Chinchilla rabbits as an experimental model of this type of keratitis. Chemical constituents of the aqueous extract of
A. cepa
were identified using Liquid Chromatography-mass Spectrometry (LC-MS). In vitro
, A. cepa
showed a significant inhibitory effect on trophozoites and cysts compared to the reference drug, chlorhexidine (CHX) as well as the non-treated control (
P
< 0.05) with statistically different effectiveness in terms of treatment durations and concentrations. No cytotoxic effect of
A. cepa
on corneal cell line was found even at high concentrations (32 mg/ml) using agar diffusion method. The in vivo results confirmed the efficacy of
A. cepa
where the extract enhanced keratitis healing with complete resolution of corneal ulcers in 80% of the infected animals by day 14 (post infection)pi compared to 70% recovery with CHX after 20 treatment days. The therapeutic effect was also approved at histological, immune-histochemical, and parasitological levels. Our findings support the potential use of
A. cepa
as an effective agent against
A. spelaea
keratitis.