Letter: coeliac disease and small intestinal bacterial overgrowth ‐ is dysmotility the missing link?

We read with interest the study by Jacobs et al. suggesting that proton pump inhibitor (PPI) use and small-bowel dysmotility may be independent risk factors for developing small intestinal bacterial overgrowth (SIBO) with odds ratios of 2.72 and 2.70 respectively.1 This important work demonstrates the need for thorough investigation of patients who may have nonspecific symptoms, such as dyspepsia or IBS. We have previously demonstrated a relationship between SIBO and PPI therapy,2 but would also like to present novel data, which highlight the potential association of newly diagnosed coeliac disease (CD) with SIBO. CD patients also frequently present with nonspecific gastrointestinal symptoms3 and potential mechanisms for the association include small-bowel mucosal injury and dysmotility.4 We evaluated the relationship between newly diagnosed CD and SIBO. A total of 51 newly diagnosed CD patients (mean age 47.5; 33.3% male) prospectively underwent glucose hydrogen breath test (GHBT) prior to commencing a gluten-free diet. Results were compared with those for a control group of 125 noncoeliac patients (mean age 59; 36.8% male) undergoing GHBT for nonspecific gastrointestinal symptoms and suspected SIBO. A positive result was a rise in hydrogen of at least 20 ppm, or methane of 12 ppm. Resting hydrogen levels were similar in CD patients and controls (median 7 ppm vs. 8 ppm, P = 0.34). Eleven (21.6%) of 51 coeliac patients had a positive GHBT compared with 39 (31.2%) of 125 controls (P = 0.27). Previous studies of GHBT in healthy controls demonstrate positive results in 1% to 6%.5-8 In CD, a positive result was associated with male gender (P = 0.03), but there was no difference in presenting characteristics, biochemistry, serology or histology. Twenty-two CD patients were retested after initiating gluten-free diet (mean 200 days) without antibiotic treatment. All 17 previously negative patients remained negative, 4/5 patients with a positive baseline GBHT test remained positive. These novel data suggest that newly diagnosed CD patients have similar rates of SIBO to symptomatic patients with a high suspicion of SIBO. Small-bowel dysmotility in CD may be due to autonomic dysfunction,9, 10 which may lead to an increased risk of SIBO. GHBT does not appear to correct on a gluten-free diet and appropriate antibiotics should be considered. Declaration of personal interests: None. Declaration of funding interests: DSS has received educational grants from Dr Schar (a gluten free food manufacturer) and Tillott's Pharma (makers of a point of care test for coeliac disease) for investigator led studies.