Small bowel bacterial overgrowth syndrome (SBBOS) is a disorder characterised by excessive amounts of bacteria in the small bowel resulting in gastrointestinal symptoms.


  • Incidence: 200.00 cases per 100,000 person-years
  • Peak incidence: 70+ years
  • Sex ratio: 1:1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


Risk factors for SBBOS
  • neonates with congenital gastrointestinal abnormalities
  • scleroderma
  • diabetes mellitus

Clinical features

It should be noted that many of the features overlap with irritable bowel syndrome:


  • hydrogen breath test
  • small bowel aspiration and culture: this is used less often as invasive and results are often difficult to reproduce
  • clinicians may sometimes give a course of antibiotics as a diagnostic trial


  • correction of underlying disorder
  • antibiotic therapy: rifaximin is now the treatment of choice due to relatively low resistance. Co-amoxiclav or metronidazole are also effective in the majority of patients.