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Updated: May 3, 2026

Culturing and Maintaining Clostridium difficile in an Anaerobic Environment
Published on: September 14, 2013
Acidified nitrite: a host defence against colonization with C. difficile spores?
R Cunningham1, E Mustoe1, L Spiller1
1Microbiology Department, Plymouth Hospitals NHS Trust, Plymouth, UK.
Abstract:
Proton pump inhibitor (PPI) use increases the risk of Clostridium difficile infection (CDI) despite C. difficile spores being acid resistant. Swallowed saliva contains nitrite which reacts with gastric acid, producing bactericidal nitrogen oxides. With 5mM nitrite at pH 2 (reflecting normal gastric conditions) all C. difficile spores were killed within 15 min. No reduction in count was seen with the same nitrite concentration at pH 5, representing gastric conditions in patients taking PPIs, even after 60 min. Reduced gastric acidification of salivary nitrite may explain the increased risk of CDI in patients taking PPIs.
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