1. University of Groningen, University Medical Center Groningen, Department of Medical Microbiology, Hanzeplein 1, 9700 RB Groningen, the Netherlands
2. University of Groningen, University Medical Center Groningen, Center for Dentistry and Oral Hygiene, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
3. University of Groningen, University Medical Center Groningen, Department of Rheumatology and Clinical Immunology, Hanzeplein 1, 9700 RB Groningen, the Netherlands