IBS 101: Post-Infectious IBS

Many people in this subgroup of IBS can actually pinpoint the onset of their symptoms.

Post-infectious IBS (PI-IBS) manifests as an irritable bowel syndrome diagnosis arising in the months after one of three types of gastrointestinal infection (infectious enteritis) in those who did not previously have IBS. 

The infections associated with PI-IBS include:

Bacterial - Salmonella, Campylobacter jejuni

Viral - Norwalk virus

Parasitic  - Giardia (duodenalis or lamblia)

These types of infections typically arise from foodborne illness (contaminated food/water) and may be acquired while traveling to certain regions of the world.

In fact,  PI-IBS is often among the most frequently diagnosed ailments in post-travel clinics.

About 1 in 10 people who suffer from infectious enteritis will go on to develop PI-IBS, with the precise risk depending on the severity of illness and various risk factors. 

These include, as per 2017 systematic review data out of Gastroenterology:

• Increased prevalence in females
• Younger age
• Antibiotic use 
• History of anxiety/depression
• Parasitic infection (more likely to lead to PI-IBS then bacterial, with viral among lowest risk)
• Potential genetic predisposition 

Causes

The reasons why these infections lead to IBS in certain individuals is not fully understood, but scientists believe it may be down to three primary factors.

These include, as per Gastroenterology 2009:

• Excessive inflammation of the GI tract
• Disturbance of gut-brain neuron signaling
• Disturbances in the gut microbiome (good bacterial populations reduced)

Based on more recent work [Gastroenterology 2020], however, it’s likely that there are even more factors at play.

So What Happens Next?

The totality of the literature I’ve reviewed on PI-IBS seems to point to a few key characteristics.

Firstly, most cases of PI-IBS mostly closely resemble IBS-D (diarrhea) and are often treated accordingly from the  dietary, pharmacological & medical perspective as per the patient’s symptoms. 

Second, post-infectious IBS tends to improve over a multi-year period and so the long-term prognosis is, in this sense, positive.

Finally, as it relates to any sort of  “special” management options for PI-IBS, the evidence in this regard is lacking.

A 2015 systematic review and meta-analysis out of Tropical Diseases, Travel Medicine and Vaccines found little evidence that a specific pharmacological treatment option was uniquely superior for PI-IBS.

Looking Ahead – Glutamine Supplements for PI-IBS?

Glutamine is an amino acid which occurs naturally in various foods and has been implicated in maintaining good gut health through playing a role in the maintenance of a healthy microbiome, strengthening intestinal lining and reducing inflammation.

A 2021 study published in Frontiers In Nutrition found that glutamine supplementation complimented a low FODMAP diet in reducing IBS symptoms. 

Three years prior, the Gut journal published a study comparing glutamine to placebo specifically in PI-IBS sufferers and found that 5 grams of glutamine (2x daily) over an 8 week period reduced IBS symptom severity. 

Obviously the evidence in this area is limited but provides interesting insights into potential future directions for the management of this unique and perhaps understudied member of the IBS family.