Proton pump inhibitors may increase the risk of Clostridium difficile infection by altering the gut microbiome, the largest study to date shows.

The research involving faecal samples from 1827 healthy twins found significant associations between the composition of the gut microbiota and PPI use.

The most striking association was an increase in lactobacillales, particularly streptococcaceae, in PPI users, the researchers reported in the study published in Gut.

“We hypothesise that under normal circumstances gastric acid acts as a barrier to progression down the GI tract for pharyngeal commensals and environmental bacteria, which are not well adapted to low pH,” the researchers suggested.

“Treatment with PPIs removes this barrier allowing colonisation by these bacteria further along the GI tract.”

” The described associations between PPI use and the gut microbiome warrant further research to better understand the driving mechanisms and their consequences, and are a further reason to reduce unnecessary prescribing,” they concluded.