Volume 49/Number 3/Abstract 9
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Acta Parasitologica, Vol.49, No. 3, 2004, 246-252
Abdullah Kilic(1), Mehmet Tanyuksel(1), James Sissons(2), Samantha Jayasekera(2) and Naveed A. Khan(2)* - Isolation of Acanthamoeba isolates belonging to T2, T3, T4 and T7 genotypes from environmental samples in Ankara, Turkey

(1)Gulhane Military Medical Academy School of Medicine, Division of Medical Parasitology, Etlik, Ankara, Turkey; (2)School of Biological and Chemical Sciences, Birkbeck College, University of London, London, WC1E 7HX, England, U.K.
*Corresponding author: n.khan@sbc.bbk.ac.uk

Acanthamoeba keratitis is a blinding infection that is becoming increasingly important in human health. Early diagnosis is a prerequisite for successful treatment and requires identification of Acanthamoeba at the genotypic level. The genus Acanthamoeba consists of both pathogenic and non-pathogenic species and has been recently classified into 13 different genotypes, T1-T12 and T14. More importantly, 95% of Acanthamoeba isolates that produce keratitis belong to T4 genotypes. In this study, we attempted to determine whether predominance of T4 isolates in Acanthamoeba keratitis is due to greater virulence or greater prevalence. We isolated 18 Acanthamoeba isolates from environmental samples in Ankara, Turkey and determined their pathogenic potential by means osmotolerance, temperature tolerance and in vitro cytotoxicity assays using corneal epithelial cells. Ribosomal DNA sequencing revealed that 10 isolates belong to T2, 5 belong to T3, 2 belong to T4 and one belongs to T7 genotype. As expected, T3 and T4 isolates exhibited the most pathogenic traits and were osmotolerant, temperature tolerant and exhibited severe corneal epithelial cell cytotoxicity indicating their pathogenic potential. Overall these data indicate that high frequency of T4 isolates in keratitis cases may well be due to their greater virulence. This is the first report presenting environmental distribution of Acanthamoeba in Ankara, Turkey.

KEY WORDS: Acanthamoeba, Protozoa, environmental isolates, genotypes, Turkey

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