The culprit in gastric ulcer: Helicobacter pylori

It has been two decades since Barry Marshall and Robin Warren first reported that the bacterium Helicobacter pylori is the culprit in gastritis and s ulcer. And for that reason, they were the recipients of the 2005 Nobel Prize for Medicine and Physiology. Before their seminal report, stress was said to be the main cause of gastric ulcers. The Nobel Committee in Stockholm, Sweden cited the two Australians for going against medical dogma at that time and turning peptic ulcers from a chronic debilitating disease to a treatable infection using a short course of antibiotics.

The pathologist, Warren, and the gastroenterologist, Marshall, teamed up to prove that this gram-negative, spiral-shaped bacterium was the cause of acute and chronic inflammation in the stomach. They found it hard to convince the larger medical community because conventional wisdom dictated that the stomach environment was sterile due to its extremely acidic environment. Interestingly, Marshall was able to culture the bacteria by serendipity. He accidentally left his culture specimens during one Easter holiday, giving the bacteria enough time to grow and reproduce. H. pylori is a tricky bacterium to grow and culture in stomach biopsy specimens because it is slow-growing in ordinary conditions where other bacteria can achieve optimum growth. And it thrives only in an environment with little or without oxygen. Despite being able to culture it, Marshall still found it hard to convince the scientific world. So he underwent endoscopy, inserting a fiberoptic tube to his stomach to ascertain he had no gastric lesions, ingested a test tube full of pure culture of the bacteria, and after two weeks, inserted the tube again to prove gastritis was present. Within five days of ingesting the bacteria, he had early morning nausea and vomiting and pictures from the fiberoptic scope showed acute inflammation. He did not wait for ulcers to develop. He medicated himself by taking a course of antibiotics, with the resulting eventual healing of the gastritis.

Although it took almost two decades for Warren and Marshall to be recognized for their work, their breakthrough led other scientists to find other chronic diseases that might be linked to the presence of microbes (rheumatoid arthritis, ulcerative colitis, etc.). The current field of H. pylori pathogenesis and its relation to gastroenterology has grown to include such novel experiments as the use of its toxin to study cell biology, rapid diagnostic techniques, and different vaccination strategies against the bacteria. There are now annual international scientific congresses on H. pylori and even a peer-reviewed journal, Helicobacter.

Presently, H. pylori is known not only as the cause of stomach ulcers but also of gastric cancer and cancer associated with the lymph nodes that line the stomach. Researchers have documented that patients with previous infection with the bacteria were more likely to develop gastric cancer than the normal population. Treatment of the infection in patients with cancer of the gastric lymph nodes (MALT lymphoma) resulted in remission. It must be noted that H. pylori infection is a chronic one. It starts early in childhood and if left untreated, can lead to such a deadly consequence like cancer, which is why it becomes imperative to treat such an infection early.

Colonization of the bacteria is very high in developing countries like the Philippines. The bacteria, in contrast to the 50 percent incidence in industrialized countries, colonize almost 80 percent of the population in Third World countries. Transmission is thought to be by the oral-fecal route, which is why infection is clustered in members of one family. Poor hygiene and unsanitary conditions play a huge role in the spread and development of this infection.

Every time one feels an epigastric acid type of pain, early morning nausea and vomiting, one needs to have a checkup with his/her doctor. It is understood, however, that other causes of such pain should be ruled out such as biliary stones or bleeding caused by NSAIDS (drugs that cause bleeding like indomethacin, ibuprofen, aspirin and the likes.) If peptic ulcer is suspected, one needs to do an endoscopy and document the presence of a lesion, and ideally, get samples for culturing of the bacteria. Most of the time, there is a negative culture of the bacteria so a urease test is done, too, in which one gets tested for the presence of an enzyme secreted by H. pylori called urease.

The latest recommended treatment modality for H. pylori infection involves two courses: a triple chemotherapy and quadruple therapy, depending on the condition of the patient. The former involves the use of three drugs (a proton pump inhibitor or PPI like omeprazole, and two antibiotics, clarithromycin and amoxicillin) given twice a day for one week. The latter is recommended if the triple therapy fails: four drugs (PPI, two antibiotics – metronidazole and tetracycline – and a bismuth compound) given for two weeks.

The bottom line on peptic ulcers is this: if you are suffering from it for a long time, ruling out other causes like NSAIDS, etc., you can be cured by eliminating the pathogen, H. pylori, with an antibiotic prescription from your doctor.

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Dr. Philip Ian Padilla is a graduate of the UP College of Medicine, Class 1992. He finished his Ph.D. in Medical Science (Bacteriology) at the Institute of Tropical Medicine, Nagasaki University, where he did his dissertation, which focused on the toxin (VacA) produced by Helicobacter pylori. After leaving Japan, he did a postdoctoral research fellowship in cell biology at the National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH) in Bethesda, Maryland. He is currently on study leave as an associate professor at the University of the Philippines in the Visayas (UPV), Miag-ao, Iloilo in order to finish his experiments at NHLBI. E-mail him at [email protected] or [email protected].