Despite
potentially formidable obstacles, FMT offers the most
controlled
form
of clinical intervention that can be used to test
whether
manipulation of microbiota can lead to beneficial results.
However,
to
date the exploratory attempts to use FMT have emphasized
ambitious clinical endpoints of safety and efficacy, while few
attempts
have been made to answer even the most basic techni-
cal
questions. For example, is it necessary to condition patients
with
antibiotics prior to FMT for most non-CDI indications? Which
antibiotics
should be chosen? Are there disease-specific donor
selection
criteria or markers of specific microbiota for individual
clinical
indications? Should such FMT interventions be combined
with
specific diets or lifestyle changes? Similarly, most non-CDI
conditions
being considered for FMT are extremely heterogeneous
in
terms of host genetic factors and developmental periods. Therefore,
it is critical to carefully characterize the recipient populations.
A
major distinguishing feature of CDI versus most other indications
is
the extensive antibiotic exposure in all CDI patients undergoing
FMT. Clearly, the microbial community structure is devastated
in
this population, and FMT provides a quick ecological repair. In
contrast,
most non-CDI conditions being considered for FMT studies
are associated with much more stable and resilient microbial
communities,
eventhoughtheymaynotbeoptimalforthehost.