H. pylori bacteria live in the very acidic environment of the stomach. In order to survive such an environment, H. pylori secretes an enzyme called urease, which converts the hydrochloric acid to ammonia.

The production of ammonia from the urease enzyme neutralizes the low pH (acidic) environment of the stomach. Not surprisingly, testing for H. pylori involves checking for ammonia in a patient’s exhalation.

In addition, the spiral shape of H. pylori bacteria allow them to corkscrew into the stomach lining, thus avoiding the highly acidic environment of the stomach’s outer layer.

Because the stomach lining is constantly bathed in hydrochloric acid, immune cells do not respond to the infection appropriately. Therefore, an H. pylori infection can become chronic.

H. pylori has been around for thousands of years, and infection is common. In fact, the Centers for Disease Control and Prevention (CDC) estimates that two-thirds of the world’s population harbors H. pylori, but not everyone get sick from it.

This bacterium has learned to coexist with humans for a long time.