Introduction. The stomach secretes gastric juice every day. Gastric juice consists of digestive enzymes and concentrated hydrochloric acid, which can tear apart the toughest food and microorganism.It used to be thought that the stomach contained no bacteria and was actually sterile, but H. pylori changed that view. Why and how does HP cause diseases? Let ’ s talk about HP in this lecture?
Contents General description of H.pylori Biological characteristics of H.pylori Defense mechanism of H.pylori Pathogenesis Detection and treatment Epidemiology
General description of H. pylori 1.H. pylori is a newly discovered stomach infection which was first reported by Barry Marshall and Robin Warren of Perth, Western Australia, in 1983. 2. The bacterium lives in the stomach of about half the people in the world. Many are apparently well, and most have an inflammation of the stomach lining, a condition which is called "gastritis". 3. Gastritis is the underlying condition which causes ulcers and other digestive complaints, possibly including cancer of the stomach.
Morphology and structure G- bacteria S or spiral-shaped bacterium HP have typical morphology Almost all the bacteria have the same size length:2.5~4.0μm width:0.5~1.0μm
Submicroscopic structure of H.pylori There are 2~6 flagella at one end of HP The flagella can exist at two ends during fission Flagella play important role in motion and adhesion HP is enclosed by glucocalyx after the treatment of acid
Defense mechanism of H.pylori 1. Reaction of urea hydrolysis Once H. pylori is ensconced in the mucus, it is able to fight the stomach acid that does reach it with an enzyme called urease. Urease converts urea, of which there is an abundant supply in the stomach (from saliva and gastric juices), into bicarbonate and ammonia, which are strong bases. This creates a cloud of acid neutralizing chemicals around the H. pylori, protecting it from the acid in the stomach. The reaction of urea hydrolysis is important for diagnosis of H.pylori by the breath test.
Defense mechanism of H.pylori 2. Escape of natural defense Escape means that the body's natural defenses cannot reach the bacterium in the mucus lining of the stomach. The immune system will respond to an H. pylori infection by sending white cells, killer T cells, and other infection fighting agents which cannot easily get through stomach lining. Infection fighting agents do not go away either and the immune response grows and grows. Polymorphnucleas die, and spill their destructive compounds (superoxide radicals) on stomach lining cells.
Pathogenesis Cytotoxin associated proteins(Cag A) and Vac A is the main factor of the virulence LPS also play great importance Flagellum and urease is necessary for its adhesion and inhabitation Adhesin
Treatment Treatment of H. pylori is usually simple but patients need repeated endoscopies, biopsies, and several courses of treatment with antibiotic drugs.
Epidemiology H.pylori affects about 20% of persons below the age of 40 years, and 50% of those above the age of 60 years. H.pylori is uncommon in young children. Low socio-economic status predicts H.pylori infection. Immigration is responsible for isolated areas of high revalence in some Western countries.Western countries
Animal Helicobacters As pups, dogs catch it from their mother and have gastritis. When they grow up the Helicobacter appears to be pretty harmless. However, dog and cat helicobacter have been found in humans. Don't let dogs lick you or your children on the face and mouth (nor cats). The picture on the right is a dog helicobacter from a patient who kept two red setters in his house all his life
Prospect of Helicobacter pylori The study of H.pylori has lasted for 20 years since it was found by Warren and Marshall in 1983. During the past 20 years,all the passages published on HP have reached 14000,that means the study of HP is one of the most hot fields. Try our best to conquer it!
Staff Lei Wu Wei Ma Peng Hao Hui Wang Fudi Chen Lipan Peng Xiaolei Wang Shuncui Gao Guangbin Cui Hongyan Zhao Yongjun Zhao Huaqing Wang