Helicobacter pylori (H. pylori for short) was first discovered in the stomachs of patients with gastritis & stomach ulcers nearly 25 years ago by Dr Barry J. Marshall and Dr J. Robin Warren of Perth, Western Australia. At the time (1982/83) the conventional thinking was that no bacterium can live in the human stomach as the stomach produced extensive amounts of acid which was similar in strength to the acid found in a car-battery. Marshall & Warren literally “re-wrote” the text-books with reference to what causes gastritis & gastric ulcers.
In recognition of their very important discovery, they were Awarded the 2005 Nobel Prize for Medicine & Physiology.
H. pylori is a cork-screw shaped Gram-negative bacterium which is found to be present in the stomach-lining of ~3 billion people around the world (i.e. half the world’s population) and is the most common bacterial infection of man. Many of those carrying the bacterium have little or no symptoms & are apparently well, but all without exception have inflammation of the stomach lining, a condition which is called "gastritis". Gastritis is the underlying condition which eventually causes ulcers and other digestive complaints. If a person has had an H. pylori infection constantly for 20-30 years, it can lead to cancer of the stomach. This is the reason that the World Health Organisation's (WHO) International Agency for Research into Cancer (IARC) has classified H. pylori as a “Class- I-Carcinogen” i.e. in the same category as cigarette smoking is to cancer of the lung & respiratory tract.