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.

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.