1. Division of Infectious Diseases, Department of Internal Medicine, Pusan National University School of Medicine, Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.
2. Division of Infectious Diseases, Department of Internal Medicine, Inje University College of Medicine, Inje University Busan Paik Hospital, Busan, Korea.
3. Division of Gastroenterology, Department of Internal Medicine, Pusan National University Hospital, Busan, Korea.