Acidified nitrite: a host defence against colonization with C. difficile spores?

Area of Science:

• Gastroenterology
• Infectious Diseases
• Microbiology

Background:

• Proton pump inhibitors (PPIs) are widely used medications that reduce gastric acid production.
• PPI use is associated with an increased risk of Clostridium difficile infection (CDI), a serious gastrointestinal illness.
• C. difficile spores exhibit resistance to acidic environments.

Purpose of the Study:

• To investigate the impact of gastric pH on the bactericidal activity of salivary nitrite against C. difficile spores.
• To elucidate a potential mechanism linking PPI use to increased CDI risk.

Main Methods:

• C. difficile spores were incubated with 5mM nitrite at pH 2 (simulating normal gastric conditions) and pH 5 (simulating PPI-altered gastric conditions).
• Spore viability was assessed after 15 and 60 minutes of incubation.

Main Results:

• At pH 2, 5mM nitrite completely eradicated C. difficile spores within 15 minutes.
• At pH 5, no significant reduction in C. difficile spore count was observed after 60 minutes, even with 5mM nitrite.
• These findings indicate that gastric acidity is crucial for nitrite's sporicidal activity.

Conclusions:

• The reduced acidity in the stomach of patients taking PPIs may impair the bactericidal action of salivary nitrite.
• This impaired nitrite activity, due to altered gastric pH, could contribute to the elevated risk of C. difficile infection in PPI users.
• Maintaining adequate gastric acidity may be important for preventing CDI in susceptible individuals.