Streptococcus is a bacteria that belongs to the group of gram-positive pathogens, a group that can induce completely different disease symptoms. These can range from relatively harmless tonsil infections or skin ailments to life-threatening blood poisoning and invasive diseases, such as necrotic fasciitis, a dying off of interstitial tissue. A frequent and dangerous secondary ailment caused by streptococcus infections is rheumatic fever, which can lead to irreparable heart damage.

Of particular clinical relevance are the Group A, B, C and G streptococci, as well as streptococcus pneumonia, and also the normally harmless Viridans streptococci, which is generally associated with receding gums and tooth decay. These can cause massive abscesses in the throat and damage the heart valves. S. pneumonia is one of the most important human pathogenic bacteria due to its growing resistance to antibiotics.

The research group "Medical Microbiology" is investigating a wide variety of premises to explain the little known pathogenesis mechanisms of streptococcus. In pursuit of the answers, the group uses genomic methods, such as microarrays and modern, comprehensive protein analysis (proteomics), to discover the new virulence factors of streptococci from different geographical regions or those isolated from widely different patient profiles. The research goal is to be able to explain the interaction between pathogen and host.  Here, the streptococcus virulence factor proteins are identified that are responsible, for example, for adhesion, invasion and colonization and host persistence. When the respective gene is identified and the virulence factors reproduced in the test tube, tests are conducted to see whether they induce the identical infection mechanisms. Afterwards, the infection mechanisms are studied to see how they can be selectively inhibited or prevented entirely. At the other end, mouse models are used to study the immune defense responses of the host organism. Known virulence factors can be selectively prevented with medication from exercising their function in the infection process and thus stop an infection in the host. At the same time, the molecular structures of the virulence factors and the bacteria are being researched to see if they are suitable as vaccines. Streptococci are pathogens that can induce completely different disease symptoms: Tooth decay and tonsillitis can be caused by a streptococcus infection, but so can life-threatening toxemia (blood poisoning) and cardiovalvulitis (heart valve disease). Particularly in underdeveloped countries, where the healthcare infrastructure is not so pronounced, they are responsible for a large percentage of fatalities.

Scientists in the work group "Medical Microbiology" are looking for ways to combat this problem. Various approaches are being used to tackle these pathogens. First of all, researchers are identifying the virulence factors; that is, the proteins that are responsible for the disease-causing characteristics of the bacteria. These virulence factors are potential targets for new drugs. Furthermore, researchers are also looking for molecular structures in the bacteria that could ultimately serve as a vaccine. An effective vaccine is the best way to combat an illness.

In another ongoing research project scientists are looking to develop a quick test that would tell doctors in a matter of minutes whether a patient has a harmless bacterial infection or is suffering from a more dangerous streptococcus infection. This would allow the doctor to specifically target the ailment, which makes especially good healthcare sense in developing countries where often one doctor has to look after hundreds of patients.