Clinical trials and epidemiology of community-acquired infections
Through epidemiological observations and observational studies, DZIF scientists are improving the prediction of virulence and antibiotic resistance of gastrointestinal pathogens and the risk of infection in specific groups of people.
The central theme "Clinical trials and epidemiology of community-acquired infections" currently includes three important studies. Helicobacter pylori is a widespread bacterial pathogen of the human stomach that causes chronic infections and leads to thousands of cases of gastric ulcers and gastric cancer every year.
In the HelicoPTER study, 20,000 adults are recruited in collaboration with the "National Reference Centre for Helicobacter pylori". These will not only be tested for infection with H. pylori (H. pylori prevalence), but the researchers will also investigate which H. pylori strains occur in Germany and which antibiotic resistances these strains carry. With the help of these data, algorithms will be developed to predict antibiotic resistances and virulences of H. pylori as well as to identify transmission pathways. The biosamples collected in the course of the study will be transferred to a biobank and form an important basis for further studies.
Epidemiology of Campylobacter jejuni and Campylobacter coli
A second project deals with the epidemiology of Campylobacter jejuni and Campylobacter coli, the most common acute foodborne diarrhoeal pathogens in humans worldwide. In addition to acute diarrhoeal diseases, these bacteria may also be involved in chronic inflammatory bowel diseases in humans. Antibiotic resistance is currently increasing rapidly in these and other gut pathogenic bacteria.
By analysing the genome sequences of a large number of representative clinical isolates of the two most important Campylobacter species, the scientists involved in the project will draw conclusions about the expression and new acquisition of antibiotic resistance as well as novel genetic alterations that contribute to specific antibiotic resistance phenotypes. The data obtained will be used to develop new algorithms to predict resistance and other genetic changes relevant to the pathogenicity of specific bacterial strains.
Interaction between intestinal microbiota and the immune system with decompensated liver cirrhosis
A third project is dedicated to the investigation of the interaction between intestinal microbiota and the immune system in patients with decompensated liver cirrhosis. Bacterial infections are among the most serious complications for this patient group, as their immune system is severely weakened by cirrhosis-associated immunodeficiency (CAID). One of the main causes of this immunodeficiency is the damage to the liver and the persistent systemic inflammation, which quadruples the risk of infection. These inflammations are mainly caused by the increased migration of intestinal bacteria and their metabolic products into the blood, a consequence of the disturbed intestinal barrier. It is assumed that a dysbiosis, i.e. an unfavourable change in the intestinal microbiota, facilitates the penetration of pathogens and further damages the intestinal mucosa. In particular, after implantation of a transjugular intrahepatic portosystemic shunt (TIPS), a standard therapy to reduce portal hypertension in liver cirrhosis, infections pose a significant risk for about half of the patients.
However, the long-term effects of this treatment on immune function, systemic inflammation and risk of infection have hardly been studied so far. The study therefore investigates the relationship between the composition of the gut microbiota and the risk of infections and other complications of cirrhosis after TIPS implantation. In addition, the study will examine the extent to which the therapy of portal hypertension leads to changes in systemic inflammation and the gut microbiota and how these changes affect the immune status.