Molecular characterization of Blastocystis hominis in irritable bowel syndrome patients and nursing staff in public and private clinic in Iraq.

Irritable bowel syndrome (IBS) is common gastrointestinal disorder with prevalence globally. Parasitic infection is one of the major risk factors for developing irritable bowel syndrome. We aim to estimate the incidence of Blastocystis sp. among IBS patients and nurse staff so as to assess the association between IBS and the Blastocystis infection by using microscopic and molecular techniques. Stool samples were collected from 136 people in the IBS group, 84 participates in the control group and 30 in nurse staff. The parasitic infection was recognized via a microscopic examination and confirmed by using PCR targeting SSU rRNA gene. The overall prevalence of the parasite through microscopic examination was 42.8%, including rates of 79.4%, 18.6% and 1.8% in the IBS, nurse staff and control groups, respectively. While the prevalence estimates for parasitic infections based on PCR was 46%, including rates of 74.7%, 21.7% and 3.4% in the IBS, nurse staff and control groups, respectively. The Blastocystis isolates of this study are Blastocystis hominis belong to subtype ST3 which was the predominant subtype isolated. All microscopically positive samples were also found positive by PCR, in addition eight microscopically negative samples were found positive by PCR. Hence PCR analysis was more sensitive than microscopic analyses. The rate of Blastocystis sp. using both methods was different significantly (P≤0.05). Concerning the incidence of Blastocystis sp., statistically significant association were found between nurse staff and IBS patients by using the diagnostic technique performed.