In his PhD thesis, Thomas van der Vaart (Amsterdam UMC and UMC Utrecht) described features of Staphylococcus aureus blood stream infections in a multicenter study in the Netherlands and described which patient and disease factors pose an increased risk for endocarditis, a serious complication of the disease.

The bacteria Staphylococcus aureus can cause a wide spectrum of disease. Bloodstream infection (S. aureus bacteraemia, SAB) is a serious form of S. aureus infection, potentially leading to spread of the infection to distant sites via the bloodstream. Once in the bloodstream, S. aureus can also attach itself to the valves of the heart, causing infective endocarditis (IE). IE is one of the most feared complications of SAB because of its ability to destroy cardiac tissues such as heart valves and because of the propensity for embolic complications such as cerebral stroke. In this PhD thesis, Thomas van der Vaart, MD (Amsterdam UMC and UMC Utrecht) explored how to better identify the patients with SAB who have IE or other complications.

In his PhD thesis, Van der Vaart described the clinical and epidemiological profile of SAB in a multicenter cohort of seven hospitals in the Netherlands and described which patient and disease factors pose the most risk for serious complications of the disease. He also demonstrate that clinical criteria can identify SAB patients with a very low risk of IE. Furthermore, van der Vaart and co-workers examined the impact of so-called immortal time bias on the effect of performance of a radiological test using PET/CT on mortality in patients with SAB. Next, they turned to endocarditis in general, and examined the prognostic effect follow-up blood cultures in patients with IE not caused by staphylococci. Finally, Thomas examined the diagnostic impact of searching for immunological phenomena in patients with suspected IE and evaluate the new Duke-ISCVID diagnostic criteria for IE.

Video pitch: https://youtu.be

Thomas van der Vaart pitching his PhD work

The outcomes of this PhD project are now being used in the international SNAP trial. Using the concept of an adaptive platform trial, SNAP aims to improve treatment outcomes for patients with S. aureus bloodstream infections. This trial – of which the European part is being coordinated by UMC Utrecht - is a first of its kind in that it is recruiting adults, infants and youth. The study includes sites from Australia, New Zealand, Singapore, Canada, Israel, South Africa, Europe, the UK, and has the potential to expand to other regions.

S. aureus blood stream infection

S. aureus is a bacterium that lives on the skin or in the nose. Usually this does not cause problems, but sometimes this bacterium causes an infection. When it then enters the bloodstream, we speak of a "bloodstream infection" or "bacteremia”. Doctors often use the more specific term "Staphylococcus aureus bacteremia (SAB)". Bloodstream infections with S. aureus are common worldwide and can have serious consequences for patients. According to a recent study, SAB occurs between 3,500 and 5,000 times annually in the Netherlands, with patients routinely being hospitalized and treated with intravenous antibiotics. Despite the best possible care, mortality due to SAB is high, and researchers estimate that 20-25 percent of patients with a SAB die within 30 days of infection (for the Netherlands, it means that 2-3 patients die each day due to a SAB).

PhD defense