Molecular prevalence and genotypes of Enterocytozoon bieneusi in cancer patients under chemotherapy in Aegean region of Türkiye

Abstract Background Enterocytozoon bieneusi is the most common species found in humans. Although E. bieneusi has been investigated in humans, genotype profile of E. bieneusi is not known in Türkiye. Methods In this study, we screened E. bieneusi in patients (n = 94) with different types of malignant solid tumors by Real Time PCR and then sequenced E. bieneusi positive samples. All cancer patients were undergoing chemotherapy and had diarrhea. Moreover, as control groups, we also screened E. bieneusi in patients with diarrhea (n = 50) and without diarrhea (n = 50). Results Among all patients analyzed, 33 (17%) were found to be E. bieneusi-positive. As the patients were categorized, the molecular prevalence of E. bieneusi increased to 25.5% among cancer patients with diarrhea. However, the molecular prevalence of E. bieneusi was found to be lower in patients with presenting only diarrhea (8%) and patients without diarrhea (10%). The high molecular prevalence value detected among cancer patients with diarrhea was also statistically significant compared to other patient groups (P = 0.00112 and P = 0.0269). Among the 33 Real Time PCR positive samples, 10 of them were amplified by nested PCR and among these 10 samples, 6 of them were successfully genotyped. The phylogenetic tree showed the presence of D and Type IV which were also identified in stray cats living in İzmir in our previous study. Conclusions High molecular prevalence value indicates the importance of screening stool samples of cancer patients with diarrhea for E. bieneusi and genotyping results indicate that D and Type IV are circulating between humans and cats.