H. Pylori Infection
H. Pylori Infection falls under theGut Healthcategory.
Helicobacter pylori (H. pylori) is a pathogenic bacteria that colonizes the human stomach. About 50% of adults worldwide are infected with H. pylori, but not every infection causes symptoms. However, compared to uninfected individuals, those with an infection are three to six times more likely to develop gastric cancer. 
H. pylori is capable of reducing stomach acid, which leads to gastric microbial overgrowth and higher proportions of other potentially pathogenic microbes. It can also cause the formation of biofilm—a structured collection of microbes suspended in a protective matrix—which promotes abnormal bacterial colonization in the stomach.
H. pylori infection is usually asymptomatic, but it can erode the protective coating lining the stomach, causing inflammation that leads to gastritis or peptic ulcers.
Peptic ulcers can cause intermittent dull or burning abdominal pain that lasts minutes to hours, for days or weeks at a time. These ulcers can also cause nausea, bloating, and unintentional weight loss.
H. pylori infections can be diagnosed with blood, breath, and stool tests.
Blood tests can reveal the presence of H. pylori-specific antibodies, which indicate an infection. Urea breath tests can diagnose an H. pylori infection based on abnormally-high carbon dioxide levels. Stool samples can be tested for H. pylori antigens or elevated levels of H. pylori, but the mere presence of H. pylori in the stool doesn’t confirm an active infection.
If these tests don’t provide enough information for a diagnosis, an endoscopy may also be performed to collect images and samples of the esophagus, stomach, and part of the small intestine to check for inflammation and ulcers.
H. pylori infections are commonly treated with a combination of antibiotics and proton pump inhibitors (PPI), which reduce the production of stomach acids. Bismuth (a non-antibiotic antimicrobial ingredient found in some medications for peptic ulcers) may also be included in the therapy.  These therapies are known as triple therapy or quadruple therapy, depending on how many antibiotics are included in the treatment.
Because H. pylori has developed resistance to many antibiotics, eradication is becoming more challenging, and often requires more than one round (or combination) of treatments.
There is some evidence that probiotics improve eradication rates when added to a conventional treatment regimen. Lactobacillus-containing probiotics combined with quadruple therapy (such as bismuth, antacid medication, and two antibiotics) may be the most effective combination. However, another meta-analysis found that probiotics may not increase the eradication rate, but may decrease adverse effects of triple or quadruple therapy.
High-dose vitamin C supplementation and antioxidant-rich cranberry juice improved the efficacy of conventional treatment in a small number of studies, but more research is needed.
Periodontal treatment — including professional dental cleaning and daily oral hygiene — greatly enhances the effects of traditional treatment. This is likely due to the removal of dental plaque, a biofilm which contains H. pylori that can cause reinfection when swallowed.
Researchers aren’t sure how H. pylori is transmitted, but it could be spread through unclean water and food, or through contact with infected bodily fluids such as saliva. It’s also unclear why some people develop symptoms, while others don’t.
H. pylori infection is associated with less diverse gastric (stomach) microbiota, higher relative proportions of opportunistic pathogens (microbes that can cause disease with the right conditions), and lower proportions of beneficial microbes.
It’s also linked to some functional changes, including a reduction in microbial interactions and higher levels of gastric biofilm formation (which makes it harder to treat by reducing the impact of antibiotics).
People with H. pylori infections are more likely to have or develop hypertension, non-alcoholic fatty liver disease, and subclinical atherosclerosis. It may also increase the risk of developing irritable bowel syndrome (IBS), but more research is needed to confirm this association.
H. pylori treatment may help to reduce IBS symptoms and is also associated with a reduced risk of gastric cancer. Some research shows that eradication therapy could increase the risk of developing gastroesophageal reflux disease, but other research suggests it has no effect.