Laboratory diagnosis of Acanthamoeba keratitis in Hungary

Acanthamoeba species are free-living amebae that can be found in almost every range of environments. Within this genus, numerous species are recognized as human pathogens, potentially causing Acanthamoeba keratitis (AK). AK is a corneal disease that is predominantly associated with contact lens use, the epidemiology of which is related to the specific genotype of Acanthamoeba. This study reports seven (7/16; 43.75%) positive cases. Detection of Acanthamoeba in corneal scrapings is based on cultivation and polymerase chain reaction (PCR) combined with the molecular taxonomic identification method. By PCR, seven samples were positive; cultivation was successful for five samples, probably because of the low quantity of samples. Genotype identification was carried out with a real-time fluorescence resonance energy transfer PCR assay based on sequence analysis of the 18S rRNA gene, and sensitivity and specificity were evaluated in comparison with traditional parasitological techniques. All seven detected Acanthamoeba strains belonged to the T4 genotype, the main AK-related genotype worldwide. These results confirmed the importance of a complete diagnostic protocol, including a PCR assay, for the clinical diagnosis of AK from human samples. Genotyping allowed the identification of all isolates in the T4 group, thus demonstrating the prevalence of this genotype in Hungary.