Acanthamoeba genotype T4 from the UK and Iran and isolation of the T2 genotype from clinical isolates

Abstract

The majority of the keratitis-causing Acanthamoeba isolates are genotype T4. In an attempt to determine whether predominance of T4 isolates in Acanthamoeba keratitis is due to greater virulence or greater prevalence of this genotype, Acanthamoeba genotypes were determined for 13 keratitis isolates and 12 environmental isolates from Iran. Among 13 clinical isolates, eight (61 . 5 %) belonged to T4, two (15 . 3 %) belonged to T3 and three (23 %) belonged to the T2 genotype. In contrast, the majority of 12 environmental isolates tested in the present study belonged to T2 (7/12, 58 . 3 %), followed by 4/12 T4 isolates (33 . 3 %). In addition, the genotypes of six new Acanthamoeba isolates from UK keratitis cases were determined. Of these, five (83 . 3 %) belonged to T4 and one was T3 (16 . 6 %), supporting the expected high frequency of T4 in Acanthamoeba keratitis. In total, the genotypes of 24 Acanthamoeba keratitis isolates from the UK and Iran were determined. Of these, 17 belonged to T4 (70 . 8 %), three belonged to T2 (12 . 5 %), three belonged to T3 (12 . 5 %) and one belonged to T11 (4 . 1 %), confirming that T4 is the predominant genotype (÷ 2 ¼ 4 . 167; P ¼ 0 . 0412) in Acanthamoeba keratitis.

Acanthamoeba T4 and T15 genotypes associated with keratitis infections in Italy

“…The high proportion of Rns genotype T4 strains has been described as the main factor responsible for Acanthamoeba keratitis infections in many countries, i.e. in France (8/11, plus additional recent data) [24,25], in Greece (4/5) [12], in Hong Kong (12/13) [26], and in the UK and Iran (17/24) [8], thus providing further support to the evidence that the T4 genotype plays a prominent role in the epidemiology of AK human infections.…”

“…The high proportion of T4 Acanthamoeba associated with keratitis could be attributed to its greater virulence and wide spreading in the environment with respect to other genotypes [8]. At present, also the T2, T3, T5, T6, and T11 genotypes have been associated with AK [3,[8][9][10][11][12]. The other genotypes have been found related to non-AK infections and/or environmental sources [13].…”

“…Amoebic keratitis is caused by a wide variety of Acanthamoeba spp., most of which belonging to the T4 rDNA complex [3]. The high proportion of T4 Acanthamoeba associated with keratitis could be attributed to its greater virulence and wide spreading in the environment with respect to other genotypes [8]. At present, also the T2, T3, T5, T6, and T11 genotypes have been associated with AK [3,[8][9][10][11][12].…”

Phylogenetic evidence for a new genotype of Acanthamoeba (Amoebozoa, Acanthamoebida)

“…T2 genotype seemed to be of environmental source (Stothard et al 1998;Lorenzo-Morales et al 2006); however, recently, strains of this genotype have been recovered in human cases of keratitis and encephalitis (Maghsood et al 2005;Walochnik et al 2008). Pathogenic strains seems more closely related to the strain OX-1, and Maghsood et al (2005) proposed to split the genotype T2 Fig.…”

Susceptibility of Acanthamoeba to multipurpose lens-cleaning solutions

“…Evolutionary studies have led to the identification of at least 16 genotypes (T1-T16) based on rRNA gene sequencing (Stothard et al 1998;Gast et al 2001;Booton et al 2005;Maghsood et al 2005;Corsaro et al 2010). Most cases of keratitis are associated with genotype T4 (Yu et al 2004, Molmeret et al 2005.…”