An H. pylori infection could be the reason behind your upset stomach. Thankfully, it's easy to treat and diagnose these bacteria.

There are people who have the H. pylori bacteria without having symptoms. Scientists are not sure why. "The symptoms that are most common among people who have H. pylori infection are rather obscure," says Victor Cardena, MD, PhD, associate professor of Epidemiology, University of Texas Health Science Center in Houston. "The reason is that they acquire the bacteria early on in life and get used to the symptoms-they think they're normal. It's not until after people with the infection get cured that they tell you how much better they feel."

Typically, he says the pain is located on the side of the appendix, under the rib cage, and above the navel. Though it's in the upper part of the abdomen, it's not heartburn, and it's not something going up, says Cardena.

Is It an Ulcer?

That dull, burning sensation may signal a peptic ulcer. If the pain occurs when the stomach is empty (either between meals or at night) and is temporarily relieved by eating or taking an antacid, consult your doctor. This type of abdominal pain is the most common symptom of duodenal and gastric ulcers, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

A common cause of peptic ulcers is H. pylori. This bacterium is responsible for peptic ulcers in more than 50 percent of the word's population. The other major cause: Use of non-steroidal anti-inflammatory drugs (NSAIDS). But what doesn't cause peptic ulcers is stress or spicy food—although both can aggravate ulcer symptoms.

Symptoms that warrant immediate medical care are sever stomach pain, black or bloody stools, bloody vomit, or vomit that looks like coffee grounds.

H. Pylori Infection: Diagnosis

To determine if the ulcer is caused by an H. pylori infection, your doctor will first have to rule out the role of NSAIDs in causing your symptoms. There a few non-invasive tests to detect H. pylori:

  • A blood test will determine if there are H. pylori antibodies in the blood, indicating an infection.
  • A stool sample will determine the presence of H. pylori antigens.
  • A urea breath test can determine if H. pylori is present in the stomach.

The breath test is very accurate, says Cardena. After fasting for at least an hour, the patient blows into a container to get a baseline of carbon atoms. Then the patient ingests urea via a capsule or liquid. After a few minutes, the patient exhales into a container again. The urea is labeled with carbon 13. "The H. pylori break down urea because it has an enzyme called urease. Then we basically compare the ratio of carbon 12 to carbon 13," says Cardena. "If there is no H. pylori, there is no change. If there is H. pylori, there is a change in the ratio of those gasses, because now you have more carbon 13 than there was H. pylori."

An endoscopy may be recommended for patients who are 50 years or older and are experiencing their first ulcer, according to the NIDDK. The biopsied tissue is analyzed to see if H. pylori is present. Another reason for an endoscopy is if a suspected infection is treated, but doesn't respond to therapy, says Cardena.

H. Pylori Infection: Treatment

Current treatment guidelines call for an antibiotic regimen, which is up to 90 percent effective in eradicating H. pylori. Triple therapy, a standard treatment, consists of a proton pump inhibitor (PPI) to reduce stomach acid and help heal the stomach lining, and the antibiotics clarithromycin, amoxicillin, and metronidazole eradicates the H. pylori. The course of treatment is 10 to 14 days.

A newer treatment option is quadruple therapy. This strategy employs a PPI, bismuth subsalicylate, and the antibiotics tetracycline and metronidazole over the course of 10 and 14 days.

The patient is re-tested one month after the antibiotic regimen to be sure the H. pylori is eradicated. If not, a second round of treatment or an endoscopy may be ordered. If the H. pylori is eradicated and the symptoms persist, it could mean it's something else and you need a culture to determine what's going on.

H. Pylori Infection: Complications

Peptic ulcer isn't the only concern of a H. pylori infection. In some people, the chronic infection can lead to stomach cancer.

"We see atrophy of the stomach—in other words, the stomach lining is gone—in people who have been infected for years," says Cardena. "Poor diet and H. pylori leads to those changes, and those changes will lead to stomach cancer."

H. Pylori Infection: Who's at Risk?

Children living in developing countries and in crowded, unsanitary conditions are prone to contracting H. pylori. If someone in the household has H. pylori, other family members are at risk, though it's not known how the infection is spread.

In the United States, Hispanic adults are 67 to 70 percent more likely to get an H. pylori infection—particularly those who were born in Mexico, says Cardena. If born in the U.S., the risk is still higher than non-Hispanic whites. Native Americans and other minorities have a high prevalence too. Though immigrants and minorities have a higher rate of infection, no one is immune to contracting the bacteria.

But the good news is that H. pylori can be eradicated—and the stomach cancer that results from this infection can be prevented.