Researchers are looking at personalized treatment approaches for post-infectious irritable bowel syndrome (IBS).
- Post-infectious irritable bowel syndrome (IBS)
arises after a person experiences a gastric infection, such as a norovirus
infection, food poisoning, or even COVID-19.
- Treatments can include antibiotics and
probiotics.
- A team based in Italy conducted a pilot trial
in which they sequenced the gut microbiome of patients with IBS and used
an individualized combination of antibiotics, prebiotics, and probiotics
to treat symptoms.
Patients treated with a precision approach to
post-infectious irritable bowel syndrome (IBS) reported
improved symptoms in a small cohort of 13 participants with IBS in a pilot
trial.
The researchers conducting that trial analyzed the gut
microbiomes — individuals’ “collections” of gut bacteria — of people with the
condition, and treated the overgrowth of certain bacteria with antibiotics,
while also addressing the lack of certain bacterial strains with specific probiotics and prebiotics,
in order to promote a balanced gut environment.
They
found that over a third of those treated in this personalized way experienced
complete remission of their symptoms 12 weeks after starting treatment.
Researchers presented their non-peer-reviewed results
at the European
Society of Clinical Microbiology and Infectious Diseases conference held
in Barcelona, Spain from 27-30 April.
How can we
personalize a treatment for IBS?
Researchers had previously developed testing for stool
samples to detect which strains of bacteria were present in the microbiome of
participants.
They used this to test the 13 participants and
prescribed a specific regime of one of two antibiotics to treat pathogenic
bacteria that existed at levels that were too high, as well as probiotics to
replace beneficial strains that were at levels that were too low.
Prebiotics including inulin and psyllium were
prescribed to over two thirds of participants.
At the 12
week follow-up after initiating treatment, 12 out of 13 participants
experienced an improvement in symptoms.
Symptoms reported before the treatment started were
abdominal pain, bloating, diarrhea, constipation, weight loss and dyspepsia.
After treatment, the symptoms experienced included
abdominal pain, bloating, and diarrhea. Five participants experienced total
remission of symptoms.
The researchers also reported that gut microbiome
testing showed low species diversity in 23% of participants alongside a high
abundance of Proteobacteria in
23% of the cohort, and low abundance of Firmicutes in 38% of them.
Low abundance of short-chain fatty acid(SCFA)-producing
bacteria was found in over half (54%) of the cohort, low levels of Akkermansia and Bifidobacteria were
found in 62%, and 69% of the cohort respectively.
Study author Maurizio Sanguinetti, MD, PhD,
professor of medicine and surgery at Università Cattolica del Sacro Cuore in
Rome, Italy, explained to Medical News Today:
“The idea now is to take
into account that this results are quite encouraging up to this [point] from
our point of view, we are starting a sort of randomized trial in which we use
in that group of participants, we use the microbiota-driven therapy, and in the
other group, we use a standard of care.”
What happens
in post-infectious IBS?
IBS is a chronic
condition that affects a person’s digestive system. Symptoms include
recurrent pain, changes to bowel habits.
IBS often presents with symptoms common in other
conditions. For example, people may confuse IBS
with inflammatory bowel disease (IBD).
Where IBS is a syndrome that does not cause visible
damage to the gastrointestinal tract, IBD refers to a group of diseases,
including Crohn’s disease and ulcerative
colitis, that occur when the immune system attacks
cells in the intestines.
Post-infectious
IBS is a form of IBS that occurs after a person has experienced some kind of
gastric upset that was bacterial or viral in nature, explained Vincent Young MD PhD, professor of
internal medicine and infectious disease at the University of Michigan, who was
not involved in the research.
He told MNT that: “Basically, most people accept that
[…] post-infectious IBS is the onset of symptoms compatible with irritable
bowel syndrome that occurs at some period of time — and that period of time,
depending on who’s defining it, can be 2 years — after you have an infection,
and it could be an infection with bacteria, [or] it could be [with] viruses,
such as norovirus or SARS-CoV-2, or [even with] protozoa.“
The time frame for when the infection occurred in
respect to when the symptoms appeared was loosely defined, he said.
There is currently a poor understanding of why some
people develop post-infectious IBS and others do not, explained Satish Rao, MD, PhD, a gastroenterologist and
professor of medicine at the Medical College of Georgia, Augusta University.
Rao, who was not involved in the current study,
explained to MNT that,
when we get a gastric infection, the nociceptive receptors (
“Now, for most of us, when
the illness kind of settles down, these receptors go back to sleep again, they
go dormant again; but for some reason that we don’t understand yet, in the
so-called post-infectious IBS cohort, the nociceptive receptors — which are
pain-sensitive and distension-sensitive — […] don’t go to sleep, they remain
persistently active forever. So that process is called ‘sensitization of
receptors’.”
The treatment with antibiotics and probiotics the
researchers involved in the current study offered was fairly standard for
people with post-infectious IBS, he said.
As there were no controls described in the findings
presented at the conference, it was difficult to tell whether or not
participants would have responded similarly to a standardized, rather than
personalized, treatment, he added.
“Now, I don’t know, if patients had had just sort of
standard care therapy without looking at their microbiota, what their response
rate would be, […] because there’s no comparators in this particular case,”
said Rao.
Sequencing
the microbiome in IBS: Steps forward
Rao said the research
presented at conference was a “step in the right direction,“ adding that “the
only critique [he] would have for this is [that] this [research] is just a
beginning.“
“I’m now putting on my scientific critical hat here;
what we don’t know is: What is the underlying microbiome or underlying
dysbiosis in the colon in these individuals?” Rao wondered.
He
explained that as there is significant variation between even healthy
individuals’ microbiome, it was unclear whether the dysbiosis — the imbalance
between different bacterial strains in the gut — that occurs in people with
post-infectious IBS had caused the symptoms they experienced.
“[M]y big problem, really, is how do you […] identify
what is missing or what is too much in an individual’s microbiome?” said Rao.
He added that people should have their microbiome
sequenced when they are healthy in order for research in this area to advance,
and causal factors to be identified: “[I]f we can get to that stage, I think we
will truly practise personalized medicine, and we can get much better in
targeting treatments with some of these antibiotics, probiotics or prebiotics.”
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