Genotyping of Giardia intestinalis isolated from people living in Sivas, Turkey

Abstract

Aim: The technique of polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) genotyping was used to characterise morphologically identical isolates of Giardia intestinalis from human stool samples. Materials and methods: In this study a total of 17 trophozoite samples, obtained either directly from stool samples or after excystation, or by duodenal aspiration, were used. A set of primers was chosen to amplify the different regions of triose phosphate isomerase (tpi) and a segment of the glutamate dehydrogenase (gdh) genes. A single-stranded conformational polymorphism technique was also used in an attempt to discriminate among some subgroups. Results: Only primers of the 683-bp segment of the tpi gene from the trophozoite samples were suitable for obtaining a PCR product. In the total of 17 trophozoite DNAs where the tpi gene segment was amplified, 9 belonged to assemblage A (53%) and 4 to assemblage B (23.5%). It was not possible to identify assemblages for the remaining 4 samples (23.5%). Conclusion: PCR RFLP tpi gene application was able to discriminate between G. intestinalis assemblage A and B, but not the other subgroups. Since assemblage A is the more prevalent subgroup compared with assemblage B, this subgroup can be said to be responsible for common Giardia infections in Turkey.