Could a past E. coli infection have triggered post-infectious irritable bowel syndrome (PI-IBS) given my chronic fatigue, joint pain, and daily stomach issues despite negative tests for inflammatory bowel disease (IBD) and mildly elevated Calprotectin and lactoferrin levels?

Your Symptoms Are Consistent with Post-Infectious IBS (PI-IBS), Not IBD

Your E. coli infection 10 months ago has most likely triggered post-infectious irritable bowel syndrome (PI-IBS), and your negative endoscopic evaluations combined with normalizing inflammatory markers effectively rule out inflammatory bowel disease. 1

Why This Is PI-IBS and Not IBD

Your clinical presentation fits the diagnostic criteria for PI-IBS precisely:

• New-onset gastrointestinal symptoms following documented infectious gastroenteritis (E. coli) in someone without prior IBS 1
• Negative endoscopic findings (colonoscopy, endoscopy, and pill camera) exclude IBD, which requires visible mucosal inflammation or ulceration for diagnosis 1
• Normalizing inflammatory markers support a functional rather than inflammatory process—your calprotectin decreased from 69 to 30 (normal <50), and lactoferrin at 11.5 is only mildly elevated 1
• Timeline matches perfectly: symptoms persisting at 10 months post-infection, when PI-IBS prevalence actually increases to 14.5% beyond 12 months 1

Understanding Your Specific Symptoms

Gastrointestinal Symptoms

Approximately 10% of patients develop PI-IBS after infectious enteritis, with bacterial infections like E. coli carrying higher risk than viral infections 1. The daily stomach discomfort you're experiencing represents the altered gut-brain interaction characteristic of PI-IBS, not ongoing infection or inflammation 1.

Chronic Fatigue and Joint Pain

These extraintestinal symptoms are part of the PI-IBS spectrum and likely reflect:

• Low-grade immune activation persisting after the acute infection resolved 1
• Altered serotonin metabolism affecting both gut function and systemic symptoms like fatigue 1
• Psychological stress from chronic illness, which is both a consequence and perpetuating factor in PI-IBS 1

The joint pain specifically may represent reactive arthritis-type symptoms that can accompany post-infectious gastrointestinal syndromes 1.

Why Your Tests Were Appropriately Negative

In typical PI-IBS cases without alarm features (which you don't have—no significant weight loss >10%, no GI bleeding), extensive diagnostic workup is actually discouraged 1. Your physicians appropriately performed:

• Complete endoscopic evaluation to exclude IBD (negative, as expected in PI-IBS) 1
• Fecal inflammatory markers showing mild elevation initially but normalizing, consistent with resolving post-infectious changes rather than active IBD 1
• Stool cultures would be low-yield at this point, as long-lasting infections with E. coli are uncommon 1

Expected Disease Course and Prognosis

The prognosis for PI-IBS is generally favorable, with spontaneous and gradual resolution of symptoms in most patients over time 2. However, you should understand:

• Your 2.3-fold increased risk of persistent IBS symptoms beyond 12 months compared to uninfected individuals 1
• Symptoms may fluctuate but typically improve gradually over months to years 2
• The IBS-D (diarrhea-predominant) or IBS-M (mixed) subtypes are most common after bacterial infections and tend to remain stable 1

Treatment Approach

Since there are no evidence-based pharmacologic strategies specifically proven for PI-IBS 1, treatment follows general IBS management based on your predominant bowel pattern:

If You Have Diarrhea-Predominant Symptoms:

1. Rifaximin (non-absorbable antibiotic targeting altered gut microbiota) 1
2. Ondansetron or ramosetron (5-HT3 antagonists for diarrhea control) 1
3. Loperamide for acute symptom control 1

If You Have Mixed or Constipation Symptoms:

1. Water-soluble fibers (psyllium) 1
2. Osmotic laxatives (polyethylene glycol) 1
3. Linaclotide or lubiprostone for more severe constipation 1

For All PI-IBS Patients:

• SSRIs (selective serotonin reuptake inhibitors) address both the altered serotonin metabolism in PI-IBS and any concurrent anxiety/depression 1
• Psychological therapy (cognitive behavioral therapy) targets the gut-brain axis dysfunction 1
• Antispasmodics for abdominal pain episodes 1

Critical Pitfalls to Avoid

Do not pursue repeated endoscopic procedures or extensive inflammatory marker testing without new alarm symptoms—this reinforces illness behavior and provides no additional diagnostic value 1, 3. Your negative workup is definitive.

Avoid non-specific antidiarrheal agents chronically as they may prolong mucosal exposure to altered microbiota 4.

Don't dismiss the psychological component—anxiety and depression are both risk factors for PI-IBS development and consequences of chronic symptoms, creating a perpetuating cycle 1.

When to Reassess

Return for re-evaluation only if you develop true alarm features:

• Weight loss >10% of body weight 1
• Gastrointestinal bleeding 1
• Failure to respond to standard IBS medications after 4-6 weeks 1
• New or worsening symptoms suggesting alternative diagnosis 1

Your current symptom pattern, negative comprehensive workup, and normalizing inflammatory markers provide strong reassurance that this is PI-IBS, not IBD or ongoing infection.