CASE STUDY

Bloating that won't go away

Two antibiotic courses later, his stomach still looked pregnant by dinner.

Who is Marios, and what had he already tried?

THE PROFILE

Marios, 28

Marios is 28 and works a desk job in Athens, the kind where lunch happens in ten minutes at the keyboard. Bread and cheese most days, a coffee to get through the afternoon, and a vape he reaches for between meetings. His bloating and constipation started about a year and a half before he came to see me, and by then he had already been through two rounds of a standard gastroenterology workup.

THE PROBLEM

Two antibiotic rounds, same bloating

A gastroenterologist put him on Silactis and Colon Life, which helped for a while and then stopped working the moment he came off them. A breath test came back positive for small intestinal bacterial overgrowth, so he did a course of amoxicillin and metronidazole with a probiotic, then repeated a similar antibiotic and probiotic combination a second time when the bloating returned. Both rounds eased things for a while, and both times the bloating that won't go away came right back. Along the way he also mentioned frequent migraines and cold sores that flared whenever he was under pressure at work.

WHAT THE TESTS ALREADY SHOWED

Clean scopes, one exception

A gastroscopy in June 2018 found nothing beyond Helicobacter pylori, and a colonoscopy that September came back completely clean. Every visit ended the same way, with the same sentence: your tests are clean, it's probably just stress.

IBSyncrasy book cover

The method behind cases like this

In IBSyncrasy I go through why gut findings like these get missed after two clean scopes and repeated antibiotics, and what actually helps. Buy IBSyncrasy

Why did I decide to look deeper?

  1. 1

    About 18 months before

    Bloating and constipation begin, worsening gradually.

  2. 2

    Soon after

    Silactis and Colon Life prescribed. Improvement, then relapse after stopping.

  3. 3

    A few months later

    A gastroscopy shows Helicobacter pylori, nothing else. A SIBO breath test comes back positive.

  4. 4

    Right after that

    Amoxicillin and metronidazole with a probiotic. Symptoms ease, bloating persists.

  5. 5

    After the relapse

    A different probiotic paired with a repeat antibiotic combination. Same pattern.

  6. 6

    Around the same time

    A colonoscopy comes back completely clean.

  7. 7

    First visit with me

    Full history taken. A molecular stool panel and immune and metabolic markers are ordered.

The pattern is what caught my attention, more than any single symptom. Marios had already done exactly what a standard workup asks for, twice, and the bloating kept coming back on schedule.

What the standard workup left open

A clean gastroscopy and a clean colonoscopy rule out ulcers, visible inflammation, and structural disease. They say nothing about bacterial balance, enzyme activity, or mucosal immune markers like secretory IgA.[1] In my experience, a third round of the same antibiotics rarely changes a pattern like this, it just resets the clock on the same relapse.

How SIBO comes back after one course of antibiotics

0%12.6%27.5%43.7%
Baseline3 months6 months9 months

Lauritano EC, et al. Am J Gastroenterol. 2008;103(8):2031-2035

What I decided to check instead

After two rounds of antibiotics gave the same result, I ordered a molecular stool panel to look at what species were actually overgrown, along with secretory IgA, complement C3, homocysteine, folate, and fecal beta-glucuronidase.[2] Every one of these markers was new territory, absent from his previous workup.

What finally explained the bloating that won't go away?

The results came back a few weeks later and pointed, for the first time, to specific, measurable targets.

Enterococcus faecium (stool molecular panel) Overgrown
This species has been linked to gastrointestinal infections, prostatitis, and septic arthritis, though certain strains also play a normal role in nutrient absorption. Never measured in the earlier workup.
Secretory IgA (sIgA) Very low
sIgA is the first line of antibody defense on every mucosal surface, gut, airway, and beyond. A low reading points to weaker mucosal defense and a higher chance of both intestinal and systemic infection risk.
Bacillus species (stool molecular panel) Overgrown
These strains are sensitive to plant tannins such as green tea and to berberine. They can reduce nitrates to nitrites, so processed meats containing sodium nitrite tend to feed this overgrowth.
Fecal beta-glucuronidase Elevated
This enzyme frees hormones and other compounds the liver had already tagged for excretion, returning them to circulation. Never measured before.
Homocysteine Elevated
An independent cardiovascular risk marker. Flagged for the treating physician to monitor alongside folate replacement.
Folate Very low
Low folate tracks with the elevated homocysteine above and needs replacing directly.
Complement C3 Low
C3 supports the immune response to infections and toxins. Low levels can leave the door open to more frequent infections.
Repeat gastroscopy for H. pylori eradication — recommended Not yet done
Recommended as a next step given the original positive result and its documented association with migraine risk.[3]
REAL QUESTION

If my colonoscopy and gastroscopy were clean, how can something still be wrong in my gut?

Colonoscopy and gastroscopy are built to find structural problems: ulcers, polyps, visible inflammation, tumors. Bacterial balance, enzyme activity, and immune markers like secretory IgA show up on a stool or blood panel instead, and a gut can look completely normal on camera while carrying exactly that kind of imbalance. That gap is exactly why a molecular stool panel made sense here even after two clean scopes, and it is worth asking about whenever the same clean result keeps repeating without an explanation for the symptoms.

If your bloating followed the same pattern of antibiotics, probiotics, and clean scans, an assessment can show whether the same markers apply to you. Book an appointment

The intervention plan

The plan builds directly on these seven findings: bring down the overgrown species, replace the missing folate while the treating physician tracks homocysteine, normalize the probiotic culture, and directly inhibit beta-glucuronidase, since this enzyme is central to how hormones and toxins recirculate through the body.

How fecal beta-glucuronidase reaches beyond the gut

Urine estrone vs. fecal beta-glucuronidaseR=0.36
Beta-glucuronidase vs. fecal total estrogensR=-0.47
Deconjugated fecal estrone vs. urine estrogensR=-0.50
Microbiome richness vs. urine estrogensR≥0.50

Flores R, et al. J Transl Med. 2012;10:253

Diagram of beta-glucuronidase enzyme freeing a conjugated hormone for reabsorption toward the brain
Once beta-glucuronidase cleaves the tag the liver attached, the freed molecule can re-enter circulation, a pathway that plausibly reaches as far as neuroinflammatory processes implicated in migraine.

The treatment

InterventionFor which finding, and why
Berberine Complex 400 mgFor the Bacillus overgrowth. This genus is sensitive to berberine, which helps bring the population back down.
Probiota Sensitive SCD and GAPSFor the very low sIgA and the broader dysbiosis. Aims to normalize the probiotic culture and support mucosal defense, the same defense that matters for his frequent cold sores.
MethylB12 and methylfolateFor the low folate and elevated homocysteine, replacing what is missing while the treating physician monitors the homocysteine trend.
Calcium D-glucarateFor the elevated fecal beta-glucuronidase, inhibiting the enzyme directly so fewer already-tagged compounds get pulled back into circulation.
5-HTP SynergySupports the serotonin pathway, one of the stated goals alongside the antimicrobial and immune work.
Intestinal RepairGeneral mucosal support for the intestinal lining while the rest of the protocol takes effect.

I explained the results to Marios in the order they mattered to him: first the overgrowth driving the bloating, then the weak mucosal defense that likely plays into how often his cold sores flare, then the beta-glucuronidase finding as a plausible piece of the migraine picture that deserves watching over time. Stress is a well-documented trigger for herpes simplex reactivation in its own right,[4] so supporting mucosal immunity works alongside stress management as one part of the picture.

What actually changed the picture?

🔴 Gut finding: H. pylori positive, SIBO test positive, otherwise unremarkable

🔴 Immune and metabolic markers: never tested

🔴 Explanation for the bloating: none, tests kept coming back clean

Why is this approach likely to work?

This case is working so far because the plan follows the findings uncovered in the stool and immune panel.[2] Overgrowth, weak mucosal defense, and an enzyme running hot are three separate, addressable targets that explain the pattern.

What this means in practice

In my experience, patients who hear “your tests are clean” for over a year are almost always missing one of these three markers.[1]

NEXT STEP

Your bloating might have a specific, testable cause

In the assessment we look at exactly the markers that were missing from Marios's case before the stool panel, secretory IgA, and the rest.

Book an appointment

Frequently asked questions

Antibiotics bring down the bacterial overgrowth itself. What let it build up in the first place, whether that is motility, diet, or an unmeasured immune or enzymatic factor, usually needs its own look to hold the improvement. Relapse rates after a single antibiotic course are well documented in the literature. The treating physician decides whether repeat antibiotics, a different regimen, or further testing fits a given case.

Yes, this is common. Colonoscopy and gastroscopy are designed to detect structural problems such as ulcers or visible inflammation. Bacterial composition, enzyme activity, and immune markers need their own tests to show up, so a clean result on both still leaves room for a testable functional cause of bloating.

There is growing research linking gut microbiota and infections such as Helicobacter pylori to migraine frequency, likely through inflammatory and neuroinflammatory pathways. This remains an active area of research, and any migraine treatment decision stays with the treating physician.

References

  1. Lauritano EC, Gabrielli M, Scarpellini E, et al. (2008). Small intestinal bacterial overgrowth recurrence after antibiotic therapy. American Journal of Gastroenterology, 103(8), 2031-2035.
  2. Flores R, Shi J, Fuhrman B, Xu X, Veenstra TD, Gail MH, Gajer P, Ravel J, Goedert JJ (2012). Fecal microbial determinants of fecal and systemic estrogens and estrogen metabolites: a cross-sectional study. Journal of Translational Medicine, 10, 253.
  3. Bawand R, Ghiasian M, Samadyan M, Qaderi S (2023). Association of Helicobacter pylori with migraine headaches and the effects of this infection and its eradication on the migraine characteristics in adults: a comprehensive systematic review and meta-analysis. Helicobacter.
  4. Mantis NJ, Rol N, Corthésy B (2011). Secretory IgA's complex roles in immunity and mucosal homeostasis in the gut. Mucosal Immunology, 4(6), 603-611.
  5. Goswami P, Ives AM, Abbott ARN, Bertke AS (2022). Stress hormones epinephrine and corticosterone selectively reactivate HSV-1 and HSV-2 in sympathetic and sensory neurons. Viruses, 14(5), 1115.
Theodoros Prevedoros
MSC BIOCHEMISTRY

THEODOROS PREVEDOROS

I work alongside gastroenterologists, pediatricians and endocrinologists. Since 2007 I have been training doctors, dietitians and health professionals across the full range of functional-medicine testing (Metabolomics, Microbiome and more).

Assessment and analysis of more than 2,500 cases since 2007. Author of IBSyncrasy. Book an appointment or find me on Instagram.