Distribution and Phylogenetic Analysis of Subtypes and Alleles of Blastocystis sp. in the Stool Samples Collected from Patients with Gastrointestinal Complaints in Izmir, Turkey

PurposeBlastocystis sp. is one of the most prevalent intestinal protozoa found in humans and many other animals. The present study aimed to examine the distribution and genetic diversity of Blastocystis sp. in stool samples from patients with gastrointestinal complaints in Izmir, Turkey.MethodsAll stool samples of 439 patients with gastrointestinal complaints were examined by native-Lugol and trichrome staining. To investigate the presence of Blastocystis sp. in stool samples, DNA was isolated, and PCR was performed with the barcode region in the SSU rRNA gene. PCR positive samples were sequenced to identify subtypes and alleles of Blastocystis sp.ResultsThe prevalence of Blastocystis sp. was found to be 16.6% (73/439) in patients with gastrointestinal complaints in Izmir, Turkey. Three different Blastocystis sp. subtypes were identified. ST3 (28/55; 51.0%) was the most common subtype followed by ST2 (19/55; 34.5%) and ST1 (8/55; 14.5%). Itching and diarrhea were the most prominent clinical symptoms in Blastocystis sp. positive patients. When clinical symptoms and subtypes were compared, diarrhea was found in 62.5%, 47.4%, and 46.4% of patients with ST1, ST2, and ST3 subtypes, respectively. In addition, itching was found in 37.5%, 32.1%, and 21.1% of patients with ST1, ST3, and ST2, respectively. Six distinct alleles were identified by allele analysis of Blastocystis 18S rRNA gene: allele 4 for ST1, alleles 9, 11, and 12 for ST2, and alleles 34 and 36 for ST3. In this study, Blastocystis sp. was detected in 16 of 21 districts, including the central and rural districts of Izmir. Although ST1 was detected in central districts, it was not found in rural districts.ConclusionThis study provides comprehensive data on the prevalence and molecular epidemiology of the genetic diversity at the level of subtypes and alleles of Blastocystis sp. in different districts of Izmir province in Turkey. To the best of our knowledge, this is the first study which evaluates the distribution of subtypes and alleles of Blastocystis sp. according to PCR and SSU rRNA gene sequencing in patients with gastrointestinal complaints in different districts of Izmir province in Turkey.

Automated summary

This study examined the distribution and genetic diversity of Blastocystis sp. in stool samples from patients with gastrointestinal complaints in Izmir, Turkey. The prevalence of Blastocystis sp. was found to be 16.6%, with three different subtypes identified. Diarrhea was the most prominent clinical symptom in Blastocystis sp. positive patients.