1. Infectious Diseases Clinic, Chulalongkorn University Dental Hospital, Chulalongkorn University, Bangkok 10330, Thailand
2. Department of Oral Medicine, Faculty of Dentistry, Chulalongkorn University, 34 Henri Dunant Road, Pathumwan District, Bangkok 10330, Thailand
3. Division of Infectious Diseases, Department of Medicine, King Chulalongkorn Memorial Hospital, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand