Abstract
Purpose: :
Acanthamoeba are free-living protozoa that cause a severe and painful form of keratitis, with the primary risk factor being contact lens wear. Clinical isolates of Acanthamoeba harbor intracellular bacteria, including Legionella species (Iovieno et al Ophthalmology, 2010). The current study examined the role of the Legionella pneumophila in Acanthamoeba keratitis.
Methods: :
L. pneumophila (strain 130b) were grown on buffered charcoal yeast extract agar and Acanthamoeba (ATCC 30868) were grown in Bacto-Casitone media. Acanthamoeba were infected in vitro with L. pneumophila and 1 x10^4 trophozoites either alone or with L .pneumophila were injected into the corneal stroma of C57BL/6 mice. Corneal opacification, cellular infiltration and replication of Acanthamoeba and L. pneumophila were subsequently determined.
Results: :
L. pneumophila replicated only in the cytoplasm and in cytoplasmic vacuoles of Acanthamoeba. Acanthamoeba trophozoites alone induced a dose and time dependent corneal opacification, and trophozoites were detected in the corneal stroma. Infection with Acanthamoeba harboring intracellular L. pneumophila resulted in more severe corneal disease than either Acanthamoeba or L. pneumophila alone.
Conclusions: :
Together, these findings demonstrate that intracellular L. pneumophila contribute to the pathogenesis of Acanthamoeba keratitis.
Keywords: Acanthamoeba • keratitis