Gastrointestinal dysmotilityHydrogen Breath TestMalnutritionProkineticsQuality of life

Small intestinal bacterial overgrowth in systemic sclerosis

  • 2019
  • Kathleen Morrisroe, Murray Baron, Tracy Frech, et al.
Why this matters for your gut health

Gut involvement affects over 90% of systemic sclerosis (SSc) patients and is the leading cause of illness and the third most common cause of death in the disease. Of all the gut problems in SSc, SIBO is one that can be improved or even eradicated if recognized early. Left untreated, it causes malnutrition and vitamin and mineral deficiencies, and it seriously harms quality of life.

Summary

This review covers the epidemiology, causes, symptoms, diagnosis and treatment of small intestinal bacterial overgrowth (SIBO) in SSc. SIBO arises from gut dysmotility and slow transit, and autoantibodies (anti-vinculin, anti-M3 receptor) may contribute. There is no agreed definition or diagnostic standard. Diagnosis usually combines symptoms, a glucose or lactulose hydrogen breath test, and a trial of antibiotics. Treatment centers on rotating antibiotics, prokinetics, and correcting nutritional deficiencies. Probiotics and IVIG are still being explored. The authors stress that most evidence comes from non-SSc populations and that better trials, biomarkers and outcome measures are needed.

Key findings

  • SIBO prevalence in SSc is about 39% (range 18%–55%).
  • Symptoms are non-specific: diarrhea, bloating, flatulence, abdominal pain and early satiety.
  • Risk factors are gut dysmotility, slow transit and PPI use. Age, sex, and limited vs. diffuse disease show no association.
  • Breath tests are imperfect: lactulose sensitivity is 52.4% and specificity 85.7%, while glucose sensitivity is 62.5% and specificity 81.7%.
  • Fecal calprotectin ≥275 predicted SIBO with sensitivity 0.93 and specificity 0.95 in one study.
  • A GSS score above 5 with diarrhea predicts breath-test-proven SIBO (sensitivity 90%, specificity 86%).
  • About two-thirds of patients improve on 10–14 day antibiotic courses, and any antibiotic gave a 2.55-fold higher response than placebo. In SSc, rotating antibiotics monthly is recommended.
  • SSc-specific studies: rifaximin eradicated SIBO in 73% at 1 month (Parodi), and norfloxacin plus metronidazole did so in 52% at 11 months (Marie).
  • Prokinetics (octreotide, prucalopride, domperidone, low-dose erythromycin) are commonly used as adjuncts.
  • Untreated SIBO can cause malnutrition (prevalence 15%–58%), with 50% mortality at 8.5 years.

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Citation

Morrisroe K, Baron M, Frech T, Nikpour M. Small intestinal bacterial overgrowth in systemic sclerosis. Journal of Scleroderma and Related Disorders. 2020;5(1):33–39. doi:10.1177/2397198319863953

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