Page 6 - Introduction to FMT

FMT Introduction

These studies highlight the role of microbiota-target therapy for reinstalling the depleted bacterial
species associated with the disease. Probiotics somehow alter the metabolism of the indigenous gut
flora, although the effect is largely restricted to limited bacterial species, and have a transient
inhabitation effect on the intestine. Nevertheless, the satisfactory outcome of treatment with FMT
suggests that feces contain a superior combination of intestinal bacterial strains and is more favorable for
repairing disrupted native microbiota by introducing a complete, stable community of intestinal micro-
organisms. Feces also harbors additional substances (proteins, bile acids, and vitamins) which might
contribute to the recovery of gut function[20].

This scenario has in fact been documented in a recent study of FMT in recurrent CDI trying to elucidate
the mechanism of action of fecal infusion[33]. The authors assessed the characteristics of fecal
microbiota before, after, and during follow-up of FMT and found the intestinal microbiota changed
persistently over time, from a less-diverse disease state (pre-FMT) to a more diverse ecosystem virtually
resembling that of fecal donors (post-FMT). Such dynamic monitoring of the intestinal microbiota helps
us to identify the key groups representing the ecosystem, as well as further illustrating that normalization
of the bowel function was accompanied by the engraftment of intestinal micro-organisms from a healthy
donor. Currently, there is significant interest in the area of FMT in IBD[34], especially with the evidence of
an impressive curable effect in some ulcerative colitis (UC) patients[35,36]. A study was conducted to
determine microbiota composition after FMT in 5 patients with UC by monitoring their fecal bacterial
communities at multiple time points[37]. The results showed that one patient had a positive response to
FMT, which was characterized by the augmentation of donor-derived microbiota, including
Faecalibacterium prausnitzii, Rosebura faecis, and Bacteroides ovatus. According to Borody et al[38]
Crohn’s disease (CD) is less responsive to FMT when compared with UC. Nonetheless, recent case reports
have shown the promising future of FMT as a rescue therapy for CD[39-41]. Data on the application of
FMT in irritable bowel syndrome (IBS) is limited to a case series of 55 patients which showed that 36% of
patients were regarded as curable while 16% had symptoms reduced[42,43]. To better understand the
role of the intestinal microbiota in the etiology and effective treatment of IBD and IBS, future controlled
trials are necessary.

For this reason, the core mechanism for the efficacy of FMT is likely to be the establishment of intestinal
bacterial strains and antimicrobial components (adhesin, immunomodulatory molecules, bacteriocin, etc.)
produced by these associated strains. Adhesin molecules can compete for sites with pathogens, leading
to them being prevented from colonizing in the intestine and rehabilitating the intestinal microbiota[5].

SAFETY OF FMT

When FMT entered the medical community, it became a relatively hot therapeutic strategy, bringing with
it both promise and controversy. According to published articles, transient adverse responses after FMT
have been reported, including mild fever, abdominal pain, diarrhea, exhaust, flatulence, and fatigue[36].
However, these adverse effects are self-limiting. De Leon et al[22] reported a UC patient

Go to: quiescent for more than 20 years who developed a flare of UC after FMT. This case gives us
cautionary information concerning FMT being used to treat CDI with UC. Moreover, a recent paper
reported a UC patient who had a cytomegalovirus infection after performing home FMT without donor
screening[44]. As extracts of feces are mediators between the donor and recipient, FMT has the potential
for transmitting occult infections even when strict donor screening is performed.

FMT Introduction