1. Department of Medicine, National University Hospital, Singapore, NUHS Tower Block, 1E Kent Ridge Road, Singapore 119228.
2. Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, s-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands
3. Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
4. Nijmegen Institute for Infection, Inflammation and Immunity (N4i), PO Box 9101, Geert Grooteplein, 6525 GA, Nijmegen, The Netherlands