Genotyping of Blastocystis species in hemodialysis patients from Makkah, Saudi Arabia

The human gut is host to a diversity of microorganisms, including a parasite called Blastocystis. While there are increasing reports characterizing Blastocystis subtypes (STs) among healthy individuals, only a few studies have investigated the Blastocystis STs in renal or dialysis patients. This study investigates the Blastocystis prevalence and STs in hemodialysis patients. Fifty healthy controls and 100 chronic kidney disease patients undergoing dialysis participated in the study. Blastocystis infection was identified by using microscopic and molecular diagnosis using 18S rRNA-PCR. Then all positive samples were sent for sequencing to identify which ST they belong to. Phylogenetic and pairwise distance analyses were performed to confirm the validity of the STs. Thirty-four hemodialysis patients were infected with Blastocystis while 17 patients in the control were infected with the parasite. All positive samples were then confirmed using PCR. Genetic sequencing analysis subsequently revealed that 66% of Blastocystis infection belonged to ST1 and ST3 (33% each), followed by ST10 (20%), and ST6 (14%). The nucleotide sequence analysis of the 385 bp 18S rRNA gene revealed a >97% identity with previously identified Blastocystis isolates. The genetic analysis showed that the 8 identified isolates correspond to previously observed alleles. Six ST1 isolates produced a high frequency of Blastocystis isolates matching allele 4, with very low genetic divergence. ST3 isolates showed relatively increased genetic diversity and matching allele 34, which is the most common allele worldwide.