A research team from Turkey has reported on an improved method of DNA extraction for Blastocystis detection in human stool samples, known as the “sand method”, comparing results to the QIAamp DNA Stool Mini Kit (Qiagen) . The study notes that, “results indicated that, the mean DNA concentrations obtained by the sand method and the commercial kit were 48 and 55 ng/μl, respectively. Also, no DNA inhibitors were detected in two methods. The sand method was capable of detecting 16 parasites per 50 mg feces. DNA samples extracted by both methods were subjected to PCR. Blastocystis spp. were detected in 11 (31.4%) of 35 samples, and perfect agreement (κ: 1.000) was found between the PCR-sand method and PCR-commercial kit method. The samples that were detected positive by PCR-sand method were successfully sequenced, and Blastocystis subtypes (STs) were identified as ST3, ST2 and ST1.
The study was published in Experimental Parasitology.
Researchers reporting in the Turkish Digest of Parasitology have noted a positive correlation between Blastocystis infection and both gastrointestinal symptoms and urticaria. The study reports, “Of the evaluated 37108 stool samples, 2573 (6.93 %) were identified to be positive for Blastocystis spp. The patients with gastrointestinal complaints comprised 68.4% of Blastocystis spp. positive samples (1.761 samples) while 30.1% of patients had dermatologic symptoms (urticaria) (776 samples). Blastocystis spp. density in the non-amplified (without using any stool concentration technique) stool samples of the patients with GIS and dermatological symptoms was as follows: 2.47%, 1.35% rare, 21.73%, 22.17% few, 49.65%, 54.29% medium, 26.27%, and 22.17% dense, respectively.” The study was published in the December 2018 of the Turkish Digest of Parasitology.
Researchers evaluating the Roche LightMix Gastro assay report that it shows promise for the detection of Blastocystis. The comparison study reports that, “EZ1® (Qiagen) and QIAamp® DNA Stool Mini Kit (Qiagen) yielded similar performances for the detection of Cryptosporidium spp. and D. fragilis, significant lower Ct values (p < 0.002) pointed out a better performance of EZ1® on the five remaining pathogens. DNA extraction using the semi-automated EZ1® procedure was faster and as efficient as the manual procedure in the seven eukaryotic enteric pathogens tested. This procedure is suitable for DNA extraction from stools in both clinical laboratory diagnosis and epidemiological study settings.” The study was published in BMC Research Notes.
A genetic study of Blastocystis obtained from a rural population in Central Mexico shows that the local population carries Blastocystis with much less genetic diversity than isolates found world-wide. The researchers report that, “we collected and targeted the SSU-rDNA region in fecal samples from this population and further compared its genetic diversity and structure with that previously observed in populations of Blastocystis ST3 from other regions of the planet. Our analyses reveled that diversity of Blastocystis ST3 showed a high haplotype diversity and genetic structure to the world level; however, they were low in the Morelos population. The haplotype network revealed a common widespread haplotype from which the others were generated recently. Finally, our results suggested a recent expansion of the diversity of Blastocystis ST3 worldwide.” The study was published in Biomed Research International.
A research team from Iran has published a study of Blastocystis in patients with Inflammatory Bowel Disease. The study reports that although infection with Blastocystis was similar in controls and IBD patients, IBD patients showed a statistically significant correlation between age and infection that was not seen in healthy controls. The study noted that, “. There was no statistically significant correlation between IBD and presence of Blastocystis (P = 0.147). There was a statistically significant correlation between age and Blastocystis colonization in the IBD group (P < 0.05), but not among healthy controls.” The paper was published in The European Journal of Clinical Microbiology and Infectious Disease.
A study of 251 stool samples collected from patients in Angola has noted a high prevalence of multiple parasites. In this study, researchers used genetic tools to genotype each of the parasites detected, creating one of the few studies to provide genotyping of multiple parasitic infections in a single paper. The researchers report that, “Prevalences of S. stercoralis, G. duodenalis, Cryptosporidium spp., and Blastocystis spp. were estimated at 21.4% (95% CI: 17.1-25.7%), 37.9% (95% CI: 32.8-43.0%), 2.9% (95% CI: 1.1-4.5%) and 25.6% (95% CI: 21.18-30.2%), respectively.” The study was published in BMC Parasites and Vectors.
Researchers from Mexico and Canada have collaborated on a review describing the relationship of intestinal microbiota and the immune system. The reviewers note that, “This review focuses on intestinal protozoa, especially those still representing a public health problem in Mexico, and their interactions with the microbiome and the host. The decrease in prevalence of intestinal helminthes in humans left a vacant ecological niche that was quickly occupied by protozoa. ….. Insights into such protection may facilitate the manipulation of microbiota components to prevent and treat intestinal protozoan infections. Here we discuss recent findings about the immunoregulatory effect of intestinal microbiota with regards to intestinal colonization by protozoa, focusing on infections by Entamoeba histolytica, Blastocystis spp, Giardia duodenalis, Toxoplasma gondii and Cryptosporidium parvum. The possible consequences of the microbiota on parasitic, allergic and autoimmune disorders are also considered.”
The review was published in the Archives of Medical Research.
An Egyptian research team has noted a significantly higher prevalence of Blastocystis infection in IBS patients. The researchers note in their study of 150 samples from IBS patients with 160 controls, that ” 42 cases (28%) showed B. hominis and 2 cases (1.3%) for D. fragilis infections. After performing the culture methods for B. hominis and D. fragilis, detections increased to 50 cases (33.3%) and 3 cases (2%), respectively. While among 150 controls 18 (12%) positive samples were detected as B. hominis.” The study was published in the Iranian Journal of Parasitology.
Although Blastocystis has been reported to be an anaerobe, studies have noted that it tolerates oxygen. Researchers from a multi-national team report that, “Although generally considered a strict or obligate anaerobe, its genome encodes an alternative oxidase. Alternative oxidases are energetically wasteful enzymes as they are non-protonmotive and energy is liberated in heat, but they are considered to be involved in oxidative stress protective mechanisms. The results demonstrate that the Blastocystis cells themselves respire oxygen via this alternative oxidase thereby casting doubt on its strict anaerobic nature. Inhibition experiments using alternative oxidase and Complex II specific inhibitors clearly demonstrate their role in cellular respiration. We postulate that the alternative oxidase in Blastocystis is used to buffer transient oxygen fluctuations in the gut and that it likely is a common colonizer of the human gut and not causally involved in IBS. Additionally the alternative oxidase could act as a protective mechanism in a dysbiotic gut and thereby explain the absence of Blastocystis in established IBS environments.” The study was published in Frontiers in Cellular and Infection Microbiology.
Although mouse models of Blastocystis infection have existed for some time, rat models have been reported less frequently. A multi-institute French Team has reported success in establishing and maintaining Blastocystis infection in rats. The team reports that, “In our experimental conditions, we were unable to infect rats using vacuolar forms of an axenically cultivated ST4 isolate, but we successfully established chronic infections of 4 week-old rats after oral administration of both ST3 and ST4 purified cysts isolated from human stool samples. The infection protocol was also applied to 4 week-old C57BL/9, BALB/C and C3H mice, but any mouse was found to be infected by Blastocystis. Minimal cyst inoculum required for rat infection was higher with ST3 (105) than with ST4 (102). These results were confirmed by co-housing experiments highlighting a higher contagious potential of ST4 in rats compared to ST3. Finally, experiments mimicking fecal microbiota transfer from infected to healthy animals showed that Blastocystis spp. could easily infect a new host, even though its intestinal microbiota is not disturbed. ” The study was published in PLOS-One.