Finding the perpetrator that causes gastritis: a medical detective story that has won a Nobel Prize.

During one’s life, many people may have encountered gastritis themselves or had relatives that have developed it. According to medical professionals, gastritis is actually an umbrella term that encompasses a number of disorders linked to the inflammation of the stomach lining. Patients with gastritis suffer from acute stomach pain, have to observe a very specific diet, and are also at risk for getting sore in the stomach or in the part of the small intestine that is located near the stomach – so-called gastric or duodenal ulcers. Ulcers are painful and potentially dangerous, as they could perforate and lead to heavy bleeding. Sometimes, gastritis or ulcers can even cause stomach cancers. 

Before the late 80s, the common medical opinion was that gastritis and associated illnesses were caused by external factors – stress, bad diet, excessive smoking. This was the general consensus – until the research led by two scientists, Robin Warren and Barry J. Marshall, has revealed that the development of gastritis is more complicated than previously thought. 

In 1982, Robin Warren was a pathologist at the Royal Perth Hospital in Australia. He has invited Barry J. Marshall, a third-year intern in internal medicine at the time, to investigate bacteria that used to regularly come up in patients with ulcers and gastritis in the hospital. This bacterium was previously seen in some mammals by Japanese scientists, but it was previously not observed in human patients with gastritis. 

When Warren and Marshall compared probes taken from healthy people and people with gastritis or ulcers, they have found that gastritis patients all had certain bacteria. After multiple efforts at cultivating these bacteria, they identified it as Helicobacter pylori. This bacterium was curved at an S shape or a spiral and was Gram negative (which means it could not be dyed by the special violet stain). It was present in 90% of patients with ulcers in the duodenum and 80% of patients with ulcers in the stomach. The researchers logically assumed that this bacterium actually causes gastritis and ulcers. Still, when they presented their discoveries, they were not believed by the medical community. 

Not only there was a general conviction that gastritis is caused by stress, but there was also a weak link in the scientists’ line of evidence. Despite their best efforts, no laboratory animals, either mice or piglets, have developed gastritis when given a broth with the bacteria inside. And according to the rules developed by the person who actually discovered the connection between microorganisms and illness – Robert Koch – to prove that a certain organism causes a particular disease, this disease has to be reproduced in a healthy laboratory animal. It was obvious that these bacteria are not infectious in the animal models that were tested. Probably, the researchers thought, H. pylori causes disease only in primates. Therefore, a human had to be infected. It was not ethical to infect a healthy volunteer. Therefore, Barry Marshall has followed the footsteps of the microbiologists of old who used to infect themselves with deadly pathogens. He has ensured he had no previous gastritis and no bacteria in his stomach and then swallowed the broth with a bacterial colony. In approximately two weeks, he has developed mild gastritis symptoms.  Using this approach, he has convincingly proven that Helicobacter pylori does indeed cause gastritis and ulcers in humans. 

This discovery has laid the groundwork for multiple studies and discoveries. The bacterium was successfully used in another species of model animal – gerbils. The presence of the model and constantly developing new methods have led to multiple new discoveries. For instance, it was revealed that in some cases, H. pylori can protect its host from gastrointestinal reflux disease. Other studies have proven these bacteria can cause stomach cancer. H. pylori was found to cover a diverse group of bacteria that have different properties. 

In total, there are more than 25,000 publications devoted to this microorganism and potential approaches to its treatment.  Based on the fact that the discovery caused a major shift in views among doctors, and that there are multiple works that cite this study, Robert Warren and Barry J. Marshall have been awarded a Nobel Prize in 2005. Thanks to their dedication and willingness to risk their health, we currently have multiple ways of treating gastritis and related disease and have a significantly better understanding of how our body works. 

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