Blastocystis and Clostridioides difficile: Evidence for a Synergistic Role in Colonization Among IBD Patients with Emphasis on Ulcerative Colitis.

BACKGROUND Regarding the controversial role of Blastocystis in inflammatory bowel diseases (IBD) patients, it seems that this protozoan may lead to an overgrowth of some non-beneficial bacteria. The current study aimed to investigate the co-existence of Blastocystis and Clostridioides difficile in IBD patients. METHODS Stool samples of 102 IBD patients were collected and cultivated for C. difficile and Blastocystis. DNA extraction was performed on positive samples and C. difficile and Blastocystis were toxinotyped and subtyped, respectively. Fisher's exact test and logistic regression were employed to calculate the correlation between the existence of Blastocystis and its subtypes (ST) with C. difficile and its type of toxins. Also, the co-existence of Blastocystis and C. difficile with the frequency of defecations was evaluated. RESULTS Blastocystis and C. difficile were observed in 17 (16.7%) and 26 (25.5%) of stool samples, respectively. From 26 C. difficilepositive isolates, 24 (92.3%) and 2 (7.7%) were tcdA+/B+ and tcdA+/B-, respectively. Also, 10 (58.8%) and 7 (41.2%) were Blastocystis ST1 and ST3, respectively. Statistically significant correlations between co-existence of Blastocystis and C. difficile and co-existence of these microorganisms and frequency of defecation (P < .035) were seen. There was no statistically significant correlation between subtypes of Blastocystis and colonization of C. difficile or its toxinotypes. CONCLUSION The co-existence of Blastocystis and C. difficile in IBD patients was observed in the current study. Moreover, it can be proposed that these microorganisms may have synergistic effects on their colonization in the gastrointestinal tract.