Monday, September 7, 2020

Salmonella and GI enviroment

Q: H2 blockers are protective against salmonella?

A) True
B) False

Answer: B

The human body has two protective layers against orally acquired infectious agents such as salmonella, one is gastric acidity and the other is normal intestinal microbial flora. 

Any condition or drug which decreases gastric acidity can make infection with salmonella more susceptible. It includes gastric surgery, use of antacids, H2 blockers, proton-pump inhibitors (PPI), and achlorhydric states. Salmonella is a unique pathogen in a way that it already posses the acid tolerance response, which means it has an ability to adapt to a lower pH. Gastric acidity still provides some room for protection. 

The overuse of antibiotics can also make the situation worse. Once and if salmonellae survive in the stomach, it has to compete with the normal intestinal microbial flora. The overuse of antibiotics can take away this protective layer and can cause severe clinical symptoms. Innocent use of prophylactic antibiotics increases this risk among tourists to countries with low community hygiene. 




1. Giannella RA, Broitman SA, Zamcheck N. Gastric acid barrier to ingested microorganisms in man: studies in vivo and in vitro. Gut 1972; 13:251. 

2. Neal KR, Briji SO, Slack RC, et al. Recent treatment with H2 antagonists and antibiotics and gastric surgery as risk factors for Salmonella infection. BMJ 1994; 308:176. 

3.  Foster JW. Low pH adaptation and the acid tolerance response of Salmonella typhimurium. Crit Rev Microbiol 1995; 21:215. 

4. Mentzing LO, Ringertz O. Salmonella infection in tourists. Prophylaxis against salmonellosis. Acta Pathol Microbiol Scand 1968; 74:405.

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