Polymerase chain reaction-based subtype diversity of Blastocystis species isolates obtained from hospitalized patients with blastocystosis

Abstract

Introduction. Blastocystis sp. is a common protozoan parasite that colonizes the intestinal tract of humans and animals and in humans nine subtypes have been described so far. Gastrointestinal symptoms and/or allergic reactions are the most common reported symptoms. It is considered that there could be a link between symptoms and the subtype of Blastocystis sp. The objective of the study was to determine the subtype of Blastocystis sp. isolates from a cohort of patients hospitalized in the University Hospital – Pleven, Bulgaria. Material and methods. Blastocystis sp. isolates were collected from hospitalized patients who were clinically referred for parasitological testing and genomic DNA was extracted from cultivated Blastocystis sp. samples. The isolated DNA was then used to perform subtype classification using known sequence-tagged site (STS) primers and RFLP analysis of small subunit (SSU) rRNA gene. Results. Blastocystis sp. was isolated from 42 out of the 261 tested patients – a prevalence of 16.09%. Out of the 42 Blastocystis sp. positive fecal samples, DNA was successfully extracted from 33. The isolated DNA belonged only to two subtypes – ST1 and ST3. No mixed subtypes were detected. Conclusions. We found that ST3 was more prevalent among patients with clinically presenting allergic diseases – 17 of the tested patients (65.38%). ST1 was isolated from patients with allergic and with gastro-intestinal symptoms.

Keywords

• blastocystis
• pcr
• subtype
• blastocystosis