• INTESTINAL MICROBIOLOGY

We read with interest the recent work by Haifer et al,1 which highlighted the importance of donor selection in determining the clinical efficacy of treating ulcerative colitis (UC) using faecal microbiota transplantation (FMT), with one donor having 100% efficacy compared with a second donor (36% efficacy). Considering the impact of COVID-19 pandemic on FMT, updated guidance including patient selection, donor recruitment and selection, FMT procedures and stool manufacturing was provided by worldwide FMT experts in international guideline by Ianiro et al.2 The US Food and Drug Administration (FDA) has recommended that FMT donor screening must include a questionnaire specifically addressing risk factors for colonisation with multidrug-resistant organisms (MDROs) and stool testing for MDROs, including extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, vancomycin-resistant enterococci (VRE), carbapenem-resistant Enterobacteriaceae (CRE) and methicillin-resistant Staphylococcus aureus (MRSA) at minimum.3 The evolution of FMT and the introduction of essential donor screening requirements by the FDA are listed in figure 1A. However, little is known on the differences in donor screening protocols in different FMT centres. Therefore, we aim to provide an update on the screening strategy for faecal donors based on emerging trends in diseases as well as to propose a set of blood and stool tests to ensure safety of the FMT procedure via systematically reviewing the existing data and with our own experience in the centre of FMT at The Chinese University of Hong Kong.

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Figure 1

(A) FDA regulation amendments and safety alerts on FMT. (B) PRISMA flow diagram for the study selection. (C) Included study stratification according to the WHO regions. (D) SARS-CoV-2 testing time points. ACG, American College of Gastroenterology; AGA, American Gastroenterological Association; ASGE, American Society for Gastrointestinal Endoscopy; EPEC, enteropathogenic Escherichia coli; ESBL, extended-spectrum β-lactamase; FDA, Food and Drug Administration; FMT, faecal microbiota transplantation; IDSA, Infectious Disease Society of America; IND, investigational new drug; MDRO, multidrug-resistant organism; RNASPG, North American Society for Paediatric Gastroenterology; NASPGHAN, North American Society For Paediatric Gastroenterology, Hepatology & Nutrition; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; RCDI, Recurrent Clostridiodes difficile infections; STEC, Shiga toxin-producing Escherichia coli.

We thus systematically reviewed (INPLASY2021120063)4 the published literature (Embase and MEDLINE through PubMed and Web of Science) and consensus documents on donor screening procedures from FMT units worldwide. Thirty-three (n=33) clinical studies (Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart, figure 1B) and 11 (n=11) consensus documents in different WHO regions (figure 1C) were compared along with our local donor screening procedure (see online supplemental appendix)

The consensus documents and national guidelines published in all WHO regions supported screening of MDROs, including ESBL, VRE, CRE and MRSAs, in potential stool donors, except the Austrian5 and Taiwan guidelines.6 There was one European study testing for other MDROs, MDR Acinetobacter baumannii.7 Considering the high prevalence of MDROs in Hong Kong, with ESBL and MRSA being 52.8% and 2.5%, respectively,8 our FMT centre is currently screening ESBL, VRE, CRE, MRSA and MDR A. baumannii. Equally, a controversy is to what limits detecting ESBL–Enterobacteriaceae in the donor, for example, in India, where >70% of the population is already colonised.9

Different practices of SARS-CoV-2 testing for potential stool donors were adopted by different stool bank centres since the COVID-19 pandemic. Currently, our biobank is following a stepwise procedure to detect SARS-CoV-2 in donors (figure 1D).

The repertoire of the optimal testing methods for infective agents is rapidly changing due to the advancement of technology and our increased understanding of the risks associated with FMTs. For example, increasingly more national consensus guidelines, including the American guideline,10 recommend the detection of Shiga toxin in Escherichia coli with PCR, which is a more sensitive method as compared with enzyme immunoassays (EIA), but with a higher cost. In addition, the detection of specific MDROs in stool samples of potential donors depends on their local prevalence and risk assessment. With the rapidly increasing numbers of FMT biobanks established worldwide, there is a need for a working consensus perhaps of a minimal set of screening questionnaire and laboratory test requirements. Here we propose (table 1) a minimum but essential set of screening questionnaire and laboratory tests in donor selection. Additional consideration made to specific conditions and tests will be based, according to a risk-based assessment, depending on the geographical prevalence of disease and other cultural and medicine licensing requirements and risk–benefit factors in their region.