Antibiotics, prebiotics, and probiotics combo may help

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Researchers are looking at personalized treatment approaches for post-infectious irritable bowel syndrome (IBS). Image credit: Olga Rolenko/Getty Images.
  • 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.

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.”

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 (nociceptors) in the gut “fire off,” meaning we get sensations from the gut that we would not normally:

“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.

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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