The first Acanthamoeba keratitis case in the Midwest region of Brazil: diagnosis, genotyping of the parasite and disease outcome

Abstract

We report an Acanthamoeba keratitis case associated with the use of contact lens in a 28-year-old female from Brasília, Brazil. Samples from corneal scraping and contact lens case were used for culture establishment, PCR amplification, and partial sequencing (fragments of ~400kb) of small subunit rDNA; both culture and PCR were positive. The sequence analyses of the cornea and of isolates from the contact lens case showed similarity with the T4 genotype. To the best of our knowledge, this is the first report of T4 Acanthamoeba keratitis case from the Midwest region of Brazil.

Acanthamoeba keratitis: a review of biology, pathophysiology and epidemiology

“…These must have a difference of at least 5% in order to be considered different sequences. 2 To date, 25 species 27 and 20 different genotypes of Acanthamoeba (T1-T20) 28,46,[49][50][51][52] have been recognised.…”

“…35 In 1988, the first incidence of this disease was announced in Japan 80 as well as the southeast and southern regions of Brazil. 51 In countries such as Japan, where the prevalence of myopia is high and orthokeratology lenses are popular, infection numbers 79 are 15 times higher than in the USA. 5,82 In China, the first case of AK was reported in 1991, 69 and the situation is similar to Japan with high numbers of patients undergoing orthokeratology for myopia control.…”

“…136-kDa MBP adheres to the exposed mannosylated glycoproteins on the surface of the corneal epithelium. 15,16,42,51,56 This event is only possible because of the high quantity of both these proteins, which are essential for the adherence of Acanthamoeba to the corneal epithelium in injured corneal surfaces. 16 Trophozoites release MIP133, a protease able to dissolve cells when exposed to mannose.…”

“…16 Stromal invasion results from the destruction of epithelial cells and the perforation of Bowman's membrane by the serine protease enzyme, as well as the secretion of collagenolytic factors from trophozoites leading to the dissolution of the stromal matrix. 10,51 This stromal degradation facilitates deeper invasion into the cornea. 3 During the process, the amoeba induces cytolytic mechanisms that cause changes in the osmotic pressure inside the cell, as well as ionic disruption causing apoptosis of the host cell.…”

“…The diagnosis of AK is complicated due to unspecific signs and symptoms. 29 AK is often confused with herpes simplex keratitis 31,51,117,138 or other forms of viral, fungal or bacterial keratitis. 2 Early diagnosis and treatment is essential to maintain vision since a delay in diagnosis may lead to a poorer prognosis, 75,139 possibly resulting in permanent blindness or the need for a corneal transplant.…”