Kératites amibiennes

Abstract

Early diagnosis and appropriate therapy are key elements for a good prognosis in Acanthamoeba keratitis (AK). AK should be considered in any case of corneal trauma complicated by exposure to soil or contaminated water, and in all contact lens (CL) wearers. A presumptive diagnosis of AK can be made clinically and with in vivo confocal microscopy, although a definitive diagnosis requires identification of Acanthamoeba on direct scraping, histology, or identification of Acanthamoeba DNA by polymerase chain reaction (PCR). We use cysticidal drugs for treating AK because encysted forms are more resistant than trophozoites to treatment. The treatment protocol used a biguanide (PHMB 0.02% or chlorhexidine 0.02%) and a diamidine (propamidine 0.1% or hexamidine 0.1%). New diagnostic modalities and more specific topical anti-amoebic treatments would substantially benefit patients with AK.

Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology

“…2,15,25,31,32 Trophozoites present vegetative growth and are characterised by having irregular, oval, round 27 or pear-shaped 5 acanthopodia (protoplasmic projections) that emerge from the clear hyaline ectoplasm laterally and anteriorly; 33 the size depends on the genotypes but is usually between 15-50 lm. 3,13,27 It includes a large number of mitocondria 2 and different kinds of vacuoles. 16 In this stage, trophozoites can replicate, move, feed or adhere to surfaces and prey through acanthopodia on the surface.…”

“…15,36 Cysts are the inactive form of Acanthamoeba that present minimal metabolic activity 2 and are the cause of persistent infections. 13 They can be found in two different forms: mature and immature. 10 The size varies depending on the genotypes, but it is generally between 5-30 lm, 13,16,27 with a stellate form having 6-8 rays, and round, ovoid, triangular, hexagonal or polygonal bodies 25,26 that vary morphologically between isolates.…”

“…13 They can be found in two different forms: mature and immature. 10 The size varies depending on the genotypes, but it is generally between 5-30 lm, 13,16,27 with a stellate form having 6-8 rays, and round, ovoid, triangular, hexagonal or polygonal bodies 25,26 that vary morphologically between isolates. The structure of the cyst contains a cellulose double wall with a fibrous laminar exocyst and a granular smooth endocyst.…”

“…2,13 It is usually uninucleate, and the nucleus stores the genetic information and controls the activities of the cell as well as the expression of different genes. 2,13 The membrane defines the limit of Acanthamoeba 13 and presents contractile vacuoles that maintain osmotic regulation by controlling water quantity inside the cell. 2,13 The pathogenicity and virulence of the amoeba can be defined by the conditions in which the species of Acanthamoeba develop and grow.…”

“…2,13 The membrane defines the limit of Acanthamoeba 13 and presents contractile vacuoles that maintain osmotic regulation by controlling water quantity inside the cell. 2,13 The pathogenicity and virulence of the amoeba can be defined by the conditions in which the species of Acanthamoeba develop and grow. 45 Pathogenicity has also been determined by observation with a scanning electron microscope (SEM) of a high quantity of surface acanthopodia.…”