Open Access Highly Accessed Research article

Small intestinal bacterial overgrowth mimicking acute flare as a pitfall in patients with Crohn's Disease

Jochen Klaus1*, Ulrike Spaniol1, Guido Adler1, Richard A Mason2, Max Reinshagen3 and Christian von Tirpitz C4

Author Affiliations

1 University Medical Center Ulm, Center for Internal Medicine, Department of Internal Medicine I, Germany

2 University Hospitals of Cleveland Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA

3 Klinikum Braunschweig, Department of Internal Medicine I, Salzdahlumer Straße 90, 38126 Braunschweig, Germany

4 Medizinische Klinik, Kreisklinik Biberach, Ziegelhausstraße 50, 88400 Biberach, Germany

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BMC Gastroenterology 2009, 9:61  doi:10.1186/1471-230X-9-61

Published: 30 July 2009



Small intestinal bacterial overgrowth (SIBO) is characterized by excessive proliferation of colonic bacterial species in the small bowel. Potential causes of SIBO include fistulae, strictures or motility disturbances. Hence, patients with Crohn's Disease (CD) are especially predisposed to develop SIBO. As result, CD patients may experience malabsorption and report symptoms such as weight loss, watery diarrhea, meteorism, flatulence and abdominal pain, mimicking acute flare in these patients.


One-hundred-fifty patients with CD reporting increased stool frequency, meteorism and/or abdominal pain were prospectively evaluated for SIBO with the Hydrogen Glucose Breath Test (HGBT).


Thirty-eight patients (25.3%) were diagnosed with SIBO based on positive findings at HGBT. SIBO patients reported a higher rate of abdominal complaints and exhibited increased stool frequency (5.9 vs. 3.7 bowel movements/day, p = 0.003) and lower body weight (63.6 vs 70.4 kg, p = 0.014). There was no correlation with the Crohn's Disease Activity Index. SIBO was significantly more frequent in patients with partial resection of the colon or multiple intestinal surgeries; there was also a clear trend in patients with ileocecal resection that did not reach statistical significance. SIBO rate was also higher in patients with affection of both the colon and small bowel, while inflammation of the (neo)terminal ileum again showed only tendential association with the development of SIBO.


SIBO represents a frequently ignored yet clinically relevant complication in CD, often mimicking acute flare. Because symptoms of SIBO are often difficult to differentiate from those caused by the underlying disease, targeted work-up is recommended in patients with corresponding clinical signs and predisposing factors.