Nowhere
is the relationship between antibiotics, host microbiota,
and human disease more clear than in the treatment of refractory
Clostridium
difficile
infection (CDI) with fecal microbiota
transplantation
(FMT). Recent investigations of patients treated
with
FMT demonstrate that there are limits to the resilience of host
microbiota
to antibiotic exposure, and that entirely new microbial
communities can be established in adult patients by direct
implantation
[1–3]. The remarkable clinical success of this procedure
in extinguishing C. difficile bacteria and achieving resolution of
associated
gastrointestinal symptoms has encouraged many investigators
and patients to imagine that FMT can result in similarly
successful
outcomes when applied to many other conditions [4].
However,
while some small observational studies do support a
degree
of optimism, it is clear that moving forward requires deeper
mechanistic
understanding of how microbial communities are held
together,
how they interact with the host, and what activities of the
microbiota
are needed for therapeutic effects in specific diseases.