The experimental production of peptic ulcers similar to human is effected since the last century. To this end have been used a number of experiments that can be grouped considering "local factors" come into play (irritating the stomach, abdominal wall trauma, exposure to X-rays, infection, obstacles in the pyloric functions and duodenal and obstacles in the circulatory system), "systemic factors" that affect the stomach and duodenum (burns, cinchophen, immunization, nutrition disorders and endocrine disorders) and their experimental production "surgical procedures" (gastroenterostomy and diversion duodenal) secretions among those considered different factors, such as nutrition, acidity, mucosal susceptibility, mechanical factor, operative trauma, jejunal spasm and protective action of duodenal secretions.

Normally bile is found in the bile ducts free of germs, only in the lower segment of the common bile duct can be found sometimes the presence of Escherichia coli, with no pathological disorders (Kirschner). In pathological circumstances bacterial infection in the different diseases of the biliary tract shows an extremely varied flora. Until now, they have agreed not authors on the predominant type of infection. Naunyn considers Bacterium coli as the main agent in inflammatory diseases of the biliary tract, and recent research consider staphylococcus (Hunter-Muller, Gundermann). The diversity of results may be explained by trying the techniques used in research, methods of storage, examination of material from autopsies and operations or the use of anaerobic media (Ozaki), missing most communications.