Introduction
The pathogenicity of Blastocystis spp. is still debated. Guidelines for donor feces screening differ in their advice to screen for Blastocystis spp., but when tested, its presence is a common reason for exclusion.1Blastocystis spp. are correlated to increased bacterial alpha-diversity2 and distinct bacterial groups3 and therefore its presence may indicate favorable efficacy of fecal microbiota transplantation (FMT). The latest European consensus report no longer advices to reject feces donors that test positive for Blastocystis spp.4 Only one paper has been published on human transmission of Blastocystis spp. via frozen FMT.5
Aims & Methods
We aimed to investigate the long-term effects of the application of Blastocystis-positive FMT, prepared with fresh feces.
In a FMT trial on FMT with refractory Irritable Bowel Syndrome (IBS) adolescents (age 16 – 20 years) received two administrations (at baseline and after 6 weeks) of fresh allogeneic FMT via nasoduodenal tube prepared with fecal samples from a Blastocystis spp. positive feces donor (NCT03074227). Blastocystis spp. presence and subtyping were determined using microscopy, PCR and Sanger sequencing.
Results
Three recipients received FMT from one donor colonized with Blastocystis subtype 3 (ST3). Two recipients were negative for Blastocystis spp. and one recipient carried ST2 at baseline prior to FMT. After FMT, the two prior-negative recipients tested positive for identical ST3 as the donor after FMT at 12 weeks, but lost carriership of this subtype at week 24 and week 48. The ST2 colonized recipient remained colonized with ST2 and did not acquire ST3 after FMT. Transient adverse events did occur, but did not differ from patients treated with Blastocystis spp.-negative FMT. No FMT-related serious adverse events occurred.
| |
Recipient |
Baseline |
Before FMT 1 | Donor
FMT 1 |
Before FMT 2 | Donor
FMT 2 | | | |
| |
| Week -2 | Week 0 | Week 0 | Week 6 | Week 6 | Week 12 | Week 24 | Week 48 |
| 1 | Woman, 18 y | negative | negative | ST3 | ST 3 | +, no seq | ST3 | negative | negative |
| 2 | Woman, 20 y | negative | negative | ST3 | +, no seq | ST3 | ST 3 | ST3 | ST3 |
| 3 | Woman, 16 y | ST2 | ST2 | ST3 | +, no seq | ST3 | ST2 | ST2 | ST2 |
Table 1: Sanger PCR sequencing results of frozen feces samples from three adolescents with IBS and one healthy donor. Samples were collected before, during and after the FMT treatment schedule with follow-up unto week 48. Light blue cells indicate a different sequence order of Blastocystis ST3 than the Blastocystis ST3 indicated in the dark blue cells. Grey cells indicate columns representing donor samples.
Abbreviations: FMT; fecal microbiota transplantation, ST; subtype, seq; sequence, y; years.
Conclusion
We present the first long-term results of Blastocystis spp. transmission by fresh FMT in three cases. Transient colonization with Blastocystis spp. did occur without the occurrence of FMT-related serious adverse events.
References
1. Benard MV, de Bruijn CMA, Fenneman AC, Wortelboer K, Zeevenhoven J, Rethans B, et al. Challenges and costs of donor screening for fecal microbiota transplantations. PLoS One. 2022;17(10):e0276323.
2. Tito RY, Chaffron S, Caenepeel C, Lima-Mendez G, Wang J, Vieira-Silva S, et al. Population-level analysis of Blastocystis subtype prevalence and variation in the human gut microbiota. Gut. 2019;68(7):1180-9.
3. Nieves-Ramirez ME, Partida-Rodriguez O, Laforest-Lapointe I, Reynolds LA, Brown EM, Valdez-Salazar A, et al. Asymptomatic Intestinal Colonization with Protist Blastocystis Is Strongly Associated with Distinct Microbiome Ecological Patterns. mSystems. 2018;3(3).
4. Keller JJ, Ooijevaar RE, Hvas CL, Terveer EM, Lieberknecht SC, Hogenauer C, et al. A standardised model for stool banking for faecal microbiota transplantation: a consensus report from a multidisciplinary UEG working group. United European Gastroenterol J. 2021;9(2):229-47.
5. Terveer EM, van Gool T, Ooijevaar RE, Sanders I, Boeije-Koppenol E, Keller JJ, et al. Human Transmission of Blastocystis by Fecal Microbiota Transplantation Without Development of Gastrointestinal Symptoms in Recipients. Clin Infect Dis. 2020;71(10):2630-6.
Disclosure
CYP has received research grants from Gilead and Perspectum, consultancy fee from Chemomab and NGM, and speaker’s fee from Tillotts. The other authors disclose no conflicts.