1. Oral Sciences Research Group, University of Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
2. Division of Human Pathology, Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
3. Laboratory of Microbiology, Department of Health Sciences, Università degli Studi di Milano, Milan, Italy