Several research trials have demonstrated that the association between small intestinal bacterial overgrowth (SIBO) and irritable bowel syndrome (IBS) is dependent on the chronic intake of proton pump inhibitors (PPIs).
However, these studies cannot be adequately compared due to the lack of information provided on the type of PPI intake, dose regimen, and the existence of a link between SIBO and IBS. Therefore, researchers recently examined the role of these pharmaceuticals in a large cohort study and found the SIBO-IBS connection to be completely independent from PPI intake.
In this prospective study, spanning over four years, 904 patients underwent upper GI tract endoscopy with sample fluid taken from the third section of the duodenum. This is the current gold standard of diagnosis for SIBO. These specimens were analysed and measured against three cut off references of 103, 104 and 105 cfu/mL colonic type bacteria.
Full medical information, including PPI intake and IBS diagnosis, assisted to determine the relationship between SIBO and IBS relative to the history of PPI use and their impact on symptomatology.
Changes in intestinal pH from PPI use are thought to promote the movement and colonisation of colonic bacteria into the proximal small intestine, leading to SIBO and IBS type symptoms.
The results revealed SIBO was significantly linked with the presence of IBS, especially in the IBS-D (diarrhoea) subtype. However, this was completely independent of PPIs, with their intake history similar in those with and without SIBO. This indicates that IBS and SIBO are strongly linked, but PPIs do not prime the development of SIBO.
Additionally, when other variables were analysed it showed a greater likelihood of SIBO in those over 60 years of age, with type 2 diabetes, or a body mass index over 22kg/m2. However, as with the PPIs, the SIBO-IBS association was independent of these factors.
Due to these results, the researchers concluded that the eradication of SIBO may be necessary in the treatment protocol for the management of IBS, with or without a history of PPI use.
- Giamarellos-Bourboulis EJ, Pyleris E, Barbatzas C, et al. Small intestinal bacterial overgrowth is associated with irritable bowel syndrome and is independent of proton pump inhibitor usage. BMC Gastroenterology 2016;16:67. [Full text]