Helicobacter pylori is a microorganism that infects the gastric mucosa, or stomach lining. This infection can lead to peptic ulcers and gastric cancer. The most unusual thing about the stomach lining is the constant turnover of the mucus and epithelial cells. So how does H. pylori manage to maintain its chronic colonization and what makes it so difficult remove? The answer is gland colonization.
Gland colonization is a unique characteristic of H. pylori. Essentially, a small number of bacterial founders establish colonies deep in the gastric glands in a narrow anatomical niche near the epithelium where the pH is near neutral. This allows the bacteria to benefit from the protective mucus layer and enables them to avoid the acidic lumen of the stomach. However, infection from H. pylori causes quite a few adverse effects on the host including inflammation, hyperplasia and even changes the gastric stem cell proliferation. Over time the infection spreads to the surface mucosa.
But what makes H. pylori infection so unique and difficult to treat? This ties back to the original gland colonies. It is believed that the primary colonies serve as stable bacterial reservoirs that can reseed the surrounding areas. In addition, H. pylori exhibit intraspecies colonization resistance by excluding isogenic competitors from this microniche. In the event that antibiotics eliminate the gland population, it only makes the space available to incoming bacteria. Furthermore, H. pylori establish stable populations within the gland microniche to generate a long-term reservoir for persistence and colonization resistance. Due to the existence of these reservoirs or “crypts,” eliminating H. pylori is a persistent problem.
Unfortunately, H. pylori is extremely difficult to remove. Due to the unique characteristics of the bacteria, it is able to create reservoirs that are protected by the biology of the stomach itself. Even if the reservoirs are eliminated, it may allow new mutant strains of H. pylori to colonize the newly cleared niches. These characteristics are the precursors to a chronic painful infection in afflicted individuals. Since H. pylori infection becomes more difficult the longer it persists, it is important to detect the infection as early as possible. Early diagnosis is the key to effective treatment before the bacteria has time to create more deeply entrenched reservoir colonies.