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 (S2 = 4.167; P = 0.0412) in Acanthamoeba keratitis.
Araki-SasakiK.,
AizawaS.,
HiramotoM. & 7 other authors; 2000; Substance P-induced cadherin expression and its signal transduction in a cloned human corneal epithelial cell line. J Cell Physiol 182:189–195[CrossRef]
BootonG. C.,
KellyD. J.,
ChuY.-W.,
SealD. V.,
HouangE.,
LamD. S. C.,
ByersT. J.,
FuerstP. A.2002; 18S ribosomal DNA typing and tracking of Acanthamoeba species isolates from corneal scrape specimens, contact lenses, lens cases, and home water supplies of Acanthamoeba keratitis patients in Hong Kong. J Clin Microbiol 40:1621–1625[CrossRef]
GastR. J.2001; Development of an Acanthamoeba -specific reverse dot-blot and the discovery of a new ribotype. J Eukaryot Microbiol 48:609–615[CrossRef]
KhanN. A.,
JarrollE. L.,
PagetT. A.2001; Acanthamoeba can be differentiated clinically by the polymerase chain reaction and simple plating assays. Curr Microbiol 43:204–208[CrossRef]
KhanN. A.,
JarrollE. L.,
PagetT. A.2002; Molecular and physiological differentiation between pathogenic and nonpathogenic Acanthamoeba
. Curr Microbiol 45:197–202[CrossRef]
KongH. H.,
ChungD. I.1996; PCR and RFLP variation of conserved region of small subunit ribosomal DNA among Acanthamoeba isolates assigned to either A.castellanii or A. polyphaga
. Korean J Parasitol 34:127–134[CrossRef]
LedeeD. R.,
HayJ.,
ByersT. J.,
SealD. V.,
KirknessC. M.1996; Acanthamoeba griffini .Molecular characterization of a new corneal pathogen. Invest Ophthalmol Vis Sci 37:544–550
SchusterF. L.,
VisvesvaraG. S.2004; Free-living amoebae as opportunistic and non-opportunistic pathogens of humans and animals. Int J Parasitol 34:1001–1027[CrossRef]
StothardD. R.,
Schroeder-DiedrichJ. M.,
AwwadM. H.,
GastR. J.,
LedeeD. R.,
Rodriguez-ZaragozaS.,
DeanC. L.,
FuerstP. A.,
ByersT. J.1998; The evolutionary history of the genus Acanthamoeba and the identification of eight new 18S rRNA gene sequence types. J Eukaryot Microbiol 45:45–54[CrossRef]
WalochnikJ.,
ObwallerA.,
AspockH.2000; Correlations between morphological, molecular biological, and physiological characteristics in clinical and nonclinical isolates of Acanthamoeba spp. Appl Environ Microbiol 66:4408–4413[CrossRef]