1. Infection Control Center, Seoul National University Hospital, Seoul, Korea.
2. College of Pharmacy, Seoul National University, Seoul, Korea.
3. Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
4. Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
5. Department of Pharmacy, Seoul National University Hospital, Seoul, Korea.
6. Department of Preventive Medicine, University of Ulsan College of Medicine, Ulsan University Hospital, Ulsan, Korea.