Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 9 4 2014 12 15 519 529 EN Hande Dagci Dept. of Parasitology, School of Medicine, Ege University, Izmir, Turkey. Özgür Kurt Dept. of Medical Microbiology, School of Medicine, Acibadem University, Istanbul, Turkey. Mete Demirel Ministry of Health's Moris Sinasi International Paediatric Hospital, Manisa, Turkey. Aliye Mandiracioglu Dept. of Public Health, School of Medicine, Ege University, Izmir, Turkey. Söhret Aydemir Dept. of Medical Microbiology, School of Medicine, Ege University, Izmir, Turkey. Ulas Saz Dept. of Paediatrics, School of Medicine, Ege University, Izmir, Turkey. Aldert Bart Dept. of Medical Microbiology, Section Parasitology, Amsterdam University, Academic Medical Center, Amsterdam, the Netherlands. Tom VAN Gool Dept. of Medical Microbiology, Section Parasitology, Amsterdam University, Academic Medical Center, Amsterdam, the Netherlands. 2015 10 14 Background: The aims of this study were to identify Blastocystis subtypes (STs) in a cohort of Turkish patients with various gastrointestinal symptoms using a novel Real Time PCR method developed recently for Blastocystis detection and assess the relationship between Blastocystis STs and patient symptoms. Methods: Totally, 617 stool samples of patients with gastrointestinal symptoms were examined with microscopy and inoculated in Jones medium. Blastocystispositive samples were further assessed to identify coinfections with other possible pathogens, including bacteria and viruses. Diagnostic efficacies of microscopy,culture and Real-Time PCR were compared. PCR products were sequenced to identify the subtypes of Blastocystis isolates. Results: Totally 94 (15.24%) samples were positive for Blastocystis after all methods.Among these, 83 of 94 (88.3%) samples were identified with all methods,while 11 were positive only with Real Time PCR. Diarrhea and abdominal pain were the leading symptoms in the patients. The only pathogenic agent identified in 76 of 94 (80.9%) patients was Blastocystis. Subtype 3 was the leading Blastocystis subtype (44.6%), while subtypes 6 and 7 were firstly isolated from symptomatic patients in our region. Conclusion: Comparison of three diagnostic methods indicated Real Time PCR as the most sensitive and specific method. Blastocystis was the only pathogenic agent among symptomatic patients, with subtype 3 being predominant. Patients with subtypes 6 and 7 need further assessments concerning the zoonotic potential of Blastocystis. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/370 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/370/375