Bacterial fingerprints across Europe

Bacterial pathogens, such as Staphylococcus aureus and carbapenemase-producing Enterobacteriaceae (CPE), impose major threats to human health worldwide. Both have a ‘Jekyll & Hyde’ character, since they can be present as human commensals, but can also become harmful invasive pathogens especially when the human host defences are impaired due to underlying diseases. Moreover, multi-drug resistant lineages have emerged not only in healthcare settings, but also in the community, sometimes causing close to untreatable infections. This calls for improved methods to detect these dangerous pathogens and to map their geographic spread. Accordingly, specific aims for the present PhD research were to apply DNA fingerprinting methods to typify highly heterogeneous S. aureus populations in Europe, to understand their epidemiology, to improve infection prevention strategies, and to avoid transmission events and outbreaks. By addressing different geographical locations, different disease groups, patient metadata including anti-staphylococcal immune responses, and different bacterial lineages and their resistance phenotypes, the molecular fingerprints of S. aureus were tracked across Europe. The use of two complementary DNA fingerprinting methods, namely multiple-locus variable number tandem repeat fingerprinting (MLVF) and spa-typing, was shown to be particularly effective to assess the genetic diversity of S. aureus. An additional aim was to obtain a first glimpse of the current spread of CPE across Europe. This was achieved through a structured survey study involving 39 European countries. Altogether, this PhD research project provided novel insights into the European epidemiology of particular S. aureus types representing high-risk clones, and the even more worrisome emergence of CPE in Europe.