[Genotyping of Giardia intestinalis isolates in the Thrace Region, Turkey]

Giardia intestinalis is a common protozoon that infects humans and may cause water and food-borne outbreaks. It is regarded as a major public health problem worldwide and in Turkey as well. Molecular techniques are widely used to determine the epidemiology, genetic populations and taxonomy of G.intestinalis. It has two genotypes including genotype A and genotype B in humans. The purpose of the present study is to implement the molecular analysis and genotyping of the isolates of G.intestinalis obtained from human stool samples. A total of 39 isolates obtained from the stool samples of persons (30 male, 9 female; age range: 1-74 years, median age: 20) who have admitted to Trakya University Medical Research and Practice Health Center and Edirne State Hospital between September 2011- April 2013 were included in the study. The average number of cysts were identified both with native and lugol methods among all microscopically detected samples by screening at least 50 field with x400 magnification. The samples were then analyzed through loop-mediated isothermal amplification method (LAMP) for the presence of elongation factor-1 alpha (EF-1α) gene, and polymerase chain reaction (PCR) method for the presence of beta-giardin (bg) gene regions. In addition, sequence analysis of bg gene was performed. Of 39 samples, 32 (82%) and 19 (48.7%) were found to be positive for G.intestinalis EF-1α and bg genes by LAMP and PCR methods, respectively. Genotyping was implemented in 17 out of 19 samples yielding nine genotype A and eight genotype B strains. The sub-genotypes of these strains were identified as A2 (n= 6), A3 (n= 3), B2 (n= 6), B3 (n= 1) and B4 (n= 1). In eight isolates that could be typed among 21 symptomatic patients, genotype B (n= 5) and in nine isolates that could be typed among 18 asymptomatic patients, genotype A (n= 6) were more frequently observed. There was no significant association between symptomatic or asymptomatic status and genotypic patterns of the cases (p= 0.347). The PCR positivity rate showed a significant difference between patients with higher cyst density and lower cyst density (p= 0.0001). In conclusion, molecular methods such as LAMP and PCR might have the potential to provide a substantial guidance for the analysis of outbreaks. In addition, the determined subtypes of G.intestinalis in our region is expected to contribute to the global epidemiological data.