What are the treatment options for patients presenting with symptoms of Post-Infectious Irritable Bowel Syndrome (PI-IBS)?

Symptoms of Post-Infectious IBS

Core Physical Manifestations

Post-infectious IBS presents with recurrent abdominal pain occurring at least 1 day per week, accompanied by altered bowel habits (predominantly diarrhea), bloating, and changes in stool consistency that develop immediately following resolution of acute infectious gastroenteritis. 1

Primary Gastrointestinal Symptoms

• Abdominal pain or discomfort that is recurrent and typically improves with defecation 1
• Altered bowel habits with diarrhea being the predominant pattern, making IBS-D the most common subtype 1
• Bloating and abdominal distension that fluctuates throughout the day 1
• Changes in stool consistency that persist after the acute infection has resolved 1

Temporal Relationship (Critical Diagnostic Feature)

• Symptoms begin immediately after and following resolution of acute infectious gastroenteritis 1
• Approximately 1 in 10 patients who experience acute gastroenteritis will develop PI-IBS 1, 2
• The infectious gastroenteritis should be defined by positive stool culture or presence of ≥2 acute symptoms: fever, vomiting, or diarrhea 3

Underlying Pathophysiological Features

These mechanisms explain why symptoms persist despite cleared infection:

• Visceral hypersensitivity causing heightened pain perception in the gut 1
• Dysmotility with altered intestinal contractions leading to diarrhea or mixed bowel patterns 1
• Persistent low-grade inflammation with ongoing immune activation despite cleared infection 1, 4
• Dysbiosis with altered gut microbiota composition 1
• Abnormal entero-endocrine signaling affecting gut-brain communication 1

Natural History and Prognosis

• Symptoms decrease over time, with better prognosis than non-PI-IBS, though resolution can take years 1
• The prognosis is somewhat better than for unselected IBS patients, but PI-IBS can still take years to resolve 2
• Physicians estimate that 4 out of 10 patients who develop PI-IBS will have life-long symptoms 5

Essential Symptom Assessment Parameters

When evaluating a patient with suspected PI-IBS, document:

• Onset, severity, and frequency using validated tools like the Gastrointestinal Symptom Rating Scale 1
• Stool frequency and consistency using the Bristol Stool Form Scale 1
• Predominant bowel pattern to classify subtype (IBS-D, IBS-M, or IBS-C) 1
• Perceived dietary triggers and their relationship to symptom exacerbation 1
• Impact on quality of life, including social and occupational functioning 1

Critical Diagnostic Pitfalls to Avoid

• Never overlook the temporal relationship between infection and symptom onset—this is the defining feature of PI-IBS 1
• Do not ignore psychological comorbidities that amplify physical symptom perception and perpetuate inflammation 1
• Avoid focusing solely on gastrointestinal symptoms while neglecting psychological factors 3

Diagnostic Confirmation Criteria

• Confirm PI-IBS diagnosis using Rome IV criteria: recurrent abdominal pain at least 1 day/week in the last 3 months, with symptom onset immediately following resolution of acute infectious gastroenteritis 3
• Perform limited baseline investigations including full blood count, C-reactive protein or ESR, coeliac serology, and faecal calprotectin (if diarrhea and age <45 years) 3