Affiliation: | a Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Graz, Austria ; b VNU-Institute of Microbiology and Biotechnology, Vietnam National University, Hanoi, Vietnam ; c Department of Periodontology and Operative Dentistry, University Hospital Münster, Münster, Germany ; d General Hospital of Nghe An Province, Nghe An, Vietnam |