Blastocystis is the most common gastrointestinal protist found in humans and animals. Although the clinical significance of Blastocystis remains unclear, the organism is increasingly being viewed as a commensal member of the gut microbiome. However, its impact on the microbiome is still being debated. It is unclear whether Blastocystis promotes a healthy gut and microbiome directly or whether it is more likely to colonize and persist in a healthy gut environment. In healthy people, Blastocystis is frequently associated with increased bacterial diversity and significant differences in the gut microbiome. Based on current knowledge, it is not possible to determine whether differences in the gut microbiome are the cause or result of Blastocystis colonization. Although it is possible that some aspects of this eukaryote’s role in the intestinal microbiome remain unknown and that its effects vary, possibly due to subtype and intra-subtype variations and immune modulation, more research is needed to characterize these mechanisms in greater detail. This review covers recent findings on the effects of Blastocystis in the gut microbiome and immune modulation, its impact on the microbiome in autoimmune diseases, whether Blastocystis has a role like bacteria in the gut–brain axis, and its relationship with probiotics.

To determine Blastocystis frequency and subtypes (ST) in ulcerative colitis (UC) patients and analyse some laboratory findings between Blastocystis positive and negative cases. Faecal samples from 150 UC patients in Adnan Menderes University, Training and Research Hospital were examined by direct microscopy and cultivated in Jones medium. Blastocystis positive cultures were subjected to DNA isolation and subtypes were identified by sequencing of barcode region. A retrospective analysis was conducted on C reactive protein (CRP), leucocyte counts (WBC), neutrophil counts, and sedimentation rates. The overall positive rate of Blastocystis was 8% (12 patients) and the most abundant subtype was ST3 (eight isolates, 66.7%), followed by ST1, ST2 and ST7. Laboratory findings between Blastocystis infected and non-infected UC patients were not significantly different. Blastocystis frequency was 3.8% among the patients in active stage, while it was 11.8% among the patients in remission stage. The present study confirms previous findings that have indicated the predominance of Blastocystis ST3 in humans and contributes additional evidence that suggests the low colonisation of Blastocystis infection in ulcerative colitis patients during active stage.

Blastocystis is an anaerobic protozoan with global importance because of infecting a variety of hosts and having high prevalence in many countries. Blastocystis isolates display remarkable genetic differences, and many subtypes (STs) have currently been defined based on polymorphism in SSU rRNA coding gene. Each 25 subtype may have different characteristics such as pathogenicity, host specificity, and structural variations. Most current research on Blastocystis has focused on these differences and molecular epidemiology. This review aimed to provide a summary of Blastocystis subtype distribution in Türkiye. Regarding human samples, 16 manuscripts were found in the literature, which presented 783 Blastocystis isolates from 9 cities in Türkiye. The most common subtype was ST3 (47.9%), the others were ST1 30 (17.5%), ST2 (14.7%), ST4 (4%), and ST5-ST7 (15.9%). There were few studies on animal hosts and environmental samples. The faecal samples from rats, farm, and pet animals were examined for Blastocystis subtypes and ST1, ST3, ST4-ST7, ST10, and ST12-ST14 were reported. In addition, two studies reported Blastocystis ST1 and ST3 subtypes in environmental water samples. In conclusion, the review of available literature showed that a systematic understanding of the subtype distribution of 35 Blastocystis in Türkiye is still lacking. Most of the studies were performed in a limited number of cities, animal hosts, and environmental samples, therefore, more studies from different provinces are needed in forthcoming research. The majority studies were performed in a limited number of provinces, animal species and very few environmental samples, so in the future; there is a need of novel studies that evaluate more samples from different provinces. Keywords: Blastocystis, subtypes, Türkiye.

Dientamoeba fragilis (D. fragilis) is a flagellated protozoan with an amoeba-like morphology, located in the gastrointestinal tract. The hypothesis was that the parasite was transported by Enterobius vermicularis (E. vermicularis) eggs. This study aimed to determine the association of D. fragilis and E. vermicularis with the genotypes of the identified strain of D. fragilis. Results of trichrome staining were compared with those of polymerase chain reaction (PCR), which is widely used in the diagnosis of D. fragilis. A total of 391 samples were obtained. The stool and cellophane slide samples were sent together to the Parasitology Department Laboratory, Faculty of Medicine, Aydın Adnan Menderes University, between 1 October 2017 and 1 October 2018. Stool samples of all patients with E. vermicularis (n=74) and without E. vermicularis (n=74) infection were used. All samples were examined for the presence of D. fragilis by trichrome staining and PCR. The 18S ribosomal RNA region of D. fragilis isolates was sequenced. Demographic characteristics and clinical findings of the patients were evaluated. D. fragilis was detected in 42 (28.37%) of 148 samples; 28 (66.6%) of them were detected in patients with E. vermicularis infection. The coexistence of two parasites was significant (p0.05). D. fragilis is frequently associated with E. vermicularis, so the presence of D. fragilis should be also considered in affected patients. The use of high-sensitivity molecular methods such as PCR is important in preventing false results. Dientamoeba fragilis (D. fragilis), amip benzeri morfolojiye sahip, gastrointestinal yerleşimli, kamçılı bir protozoondur. Parazitin Enterobius vermicularis (E. vermicularis) yumurtalarıyla taşındığı hipotezi kabul görmektedir. Çalışmamızda D. fragilis ve E. vermicularis birlikteliğini incelemek, bulunan D. fragilis’lerin genotiplerini belirlemek ve D. fragilis tanısında yaygın olarak kullanılan trikrom boyama ile polimeraz zincir reaksiyon (PZR) yöntemlerini karşılaştırmak amaçlanmıştır. Çalışmamızda Aydın Adnan Menderes Üniversitesi Tıp Fakültesi, Parazitoloji Laboratuvarı’na 1 Ekim 2017-1 Ekim 2018 tarihleri arasında dışkı ve selofan lam örneği birlikte gönderilmiş toplam 391 olgu örneği incelenmiştir. Selofanlı lam örneklerinde E. vermicularis saptanan tüm gönüllü olguların (74 olgu) dışkı örneği ile E. vermicularis negatif 74 olgunun dışkı örneği çalışılmıştır. Tüm dışkılar trikrom boyama ve PZR yöntemleri ile D. fragilis varlığı açısından incelenmiştir. Saptanan D. fragilis izolatlarının 18S ribozomal RNA bölgesi sekanslanmıştır. Olguların demografik özellikleri ve kliniği değerlendirilmiştir. Toplam 148 olgunun 42’sinde (%28,37) D. fragilis saptanmıştır. D. fragilis pozitif olan 42 olgunun %66,6’sını E. vermicularis pozitif olgular oluşturmuş ve iki parazitin birlikteliği anlamlı bulunmuştur (p0,05). Araştırmamızda D. fragilis’in sıklıkla E. vermicularis ile birliktelik gösterdiği ve bu olgularda D. fragilis varlığına ayrıca dikkat edilmesi gerektiği vurgulanmıştır. Yanlış sonuçları engellemede, yüksek duyarlılığa sahip PZR gibi yöntemlerin önemi bir kez daha görülmüştür.

Echinococcus granulosus is the causative helminth of cystic echinococcosis (CE). The parasite is known to form fluid-filled cysts that grow slowly in the internal organs, particularly the liver and/or lungs. This disease is still important in terms of public health and economically in Turkey and other countries where animal husbandry is widespread. The aim of our study was to retrospectively evaluate the cases that were admitted to the Adnan Menderes University, Training and Research Hospital Parasitology laboratory on suspicion of CE between January 2005 and January 2017. Totally, 3446 sera (from 2019 female and 1427 male) were tested with an in-house ELISA for the presence of E. granulosus specific IgG antibodies at the timeswhen they were sent. Socio-demographic characteristics (age, gender, residence, and dog ownership), positivity titers, and cyst locations of pathologically confirmed CE patients were analyzed retrospectively. The ages of patients varied between 4-87 years. It was found that 1104 (32%) of the 3446 sera were positive, and of them, 642 (58.1%) were female and 462 (41.9%) were male. Patients who had pathologically confirmed CE diagnosis constituted 247 (22.3%) of the total seropositive sera. Liver was the most commonly affected organ (81.8%), followed by lungs (6.1%). CE remains an important public health problem in our city; therefore, it is once again emphasized that preventive studies should be planned.