Research areas
Host-pathogen interaction and clinical disease in Staphylococcus aureus infection
Staphylococcus aureus remains a versatile and dangerous pathogen in humans causing community- and hospital-acquired infections with substantial morbidity and mortality. The pathogen can lead to asymptomatic carriage, but also produce disease ranging from circumscribed skin and soft tissue infections to invasive and life threatening bloodstream infections with metastatic seeding, severe sepsis and endocarditis. Our research projects focus on host-pathogen interaction in individuals with S. aureus colonisation and patients with S. aureus infections of different severity. Clinical research interests include epidemiology, diagnostic and therapeutic management and quality of care indicators in patients with S. aureus bacteremia.
The host – role of innate defense antimicrobial peptides
Antimicrobial peptides (AMPs) represent evolutionarily conserved multifunctional molecules and are an integral part of innate immunity. In humans, AMPs are expressed by cells within the epithelial lining or are delivered to sites of infection by circulating leukocytes. Our projects aim to elucidate the role of antimicrobial peptides as effector molecules of innate immunity in S. aureus colonisation and infection. In healthy colonised subjects or patients with circumscribed or systemic S. aureus infections the expression of constitutive or inducible epithelial AMPs is analysed on transcriptional and protein level. Accordingly, AMP levels of leukocytes/neutrophils in plasma or cellular extracts are analysed. Current projects are aiming to establish cell culture infection models for further analysis of host pathogen interaction in S. aureus disease.
The pathogen – characterisation of S. aureus
S. aureus possesses a broad range of virulence factors including exotoxins, adhesins and immune-modulating molecules as well as resistance genes. Our works aims to identify staphylococcal features that are associated with severe disease. Specific traits such as the susceptibility of S. aureus isolates of different clinical manifestations against innate defense antimicrobial peptides and the expression of staphylococcal multidrug resistance efflux pumps are currently investigated. In cooperation with the Department of Environmental Health and Hospital Hygiene S. aureus isolates are geno- and pathotyped using spa-typing and array technology. Parts of these projects are conducted within the DFG program ‘German-African Cooperative Projects in Infectious Diseases’ (Infection Biology and Epidemiology of Staphylococci and Staphylococcal Diseases in sub-Saharan Africa).
Staphylococcus aureus bacteremia
S. aureus bacteremia is an acute, life-threatening infection which represents an immense challenge for hospitals to provide fast and interdisciplinary management. S. aureus bacteremia carries a high risk of complications such as metastatic foci, endocarditis, severe sepsis or recurrences. The reported in-hospital mortality ranges between 20% and >30% in recent studies. Since 2006 all patients with S. aureus bacteremia are prospectively evaluated by the infectious disease consultation service and enrolled into the INvasive STapyhlococcus aureus INfections CohorT (INSTINCT, bi-center cohort in cooperation with the University of Cologne). Our research focuses on diagnostic and therapeutic management strategies and on the impact of adherence to infectious disease specialist recommendations. Additionally, we are aiming to define quality of care indicators and to identify factors indicating uncomplicated (or complicated) disease in order to stratify treatment modalities.