Restriction fragment length polymorphism (RFLP) analysis of Blastocystis spp. in symptomatic and asymptomatic individuals from Alexandria, Egypt

Abstract

Background: Blastocystis spp. is a unique enteric parasite commonly found in the intestines of humansand animals. In humans, prevalence up to 60% has been reported in tropical, subtropical, and developingcountries. Currently 26 subtypes (STs) of Blastocystis have been described based on sequence analysis, 9were reported in humans.Objectives: The aim of the work was to determine the different genotypes of Blastocystis spp. insymptomatic and asymptomatic individuals in Alexandria city, Egypt.Subjects and Methods: Examination of 100 stool samples was performed to detect Blastocystis collectedfrom patients complaining of gastrointestinal (GI) disturbances and asymptomatic individuals. PCRrestriction fragment length polymorphism analysis (PCR-RFLP) and sequencing of amplified productswas performed for Blastocystis subtyping.Results: Out of 47 fecal samples positive only for Blastocystis spp. by microscopy, 39 patients presentedwith symptoms and 8 were asymptomatic participants. Blastocystis small subunit rRNA (SSU rRNA) wassuccessfully amplified from 27 samples; 24/39 symptomatic and 3/8 asymptomatic. Among symptomaticpatients, four STs were identified; ST3 was the most common (55%) followed by ST1 (20%), ST4 (15%)and ST2 (10%). While ST2 and ST4 were identified only in patients having GI symptoms, ST1 and ST3 werefound in both symptomatic and asymptomatic participants. Amplicons of 7 samples from symptomaticpatients were not digested after incubation with the restriction enzymes and could not be genotyped.Conclusion: Genotyping of Blastocystis spp. from fecal samples revealed the presence of four differentsubtypes: ST1, ST2, ST3 and ST4 with predominance of ST3. No statistically significant association couldbe observed between Blastocystis STs and clinical presentation of the studied subjects.